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Beneficial Insects: Predators, Parasitoids, and Natural Enemies

Beneficial insects and mites can be released into the growing environment to control pest problems. Proper identification of the pest is crucial. Understanding the timing and release conditions will yield the best results.

In general, we have found that the greatest success in controlling pests occurs when the one most pest-specific parasitoid/predator is released. Occasionally, a release of several species is appropriate.

For best results, beneficial insect releases should start when pest densities are low to medium and well-timed to the appropriate life stage of the target pest. With a high pest density, it is recommended that a safe, short residual pesticide appropriate to the particular pest be applied to reduce the population of the pest before introducing the predator. It is important to note that predatory insects are susceptible to “broad-spectrum” or “non-specific” insecticides so caution should be used when selecting or applying insecticides where beneficial insects are present.

If beneficial/predatory insects are purchased, they will be sent with release instructions to most effectively utilize them. It is important that these instructions be followed.

The following information is provided as an approximate guide to determining which beneficial/predator to choose and how many to order.

Lady Beetle/Lady Bug – Convergent (Hippodamia convergens)
Lady beetles are easily identified by their shiny, half-dome shape and their short, clubbed antennae. Young lady beetle larvae usually pierce and suck the contents from their prey. Older larvae and adults chew and consume their entire prey. Larvae are active, elongate, have long legs, and resemble tiny alligators. Many lady beetles look alike and accurate identification requires a specialist.

This particular species is one of the most common Lady Beetles in North America. It is sometimes referred to as a “Ladybird Beetle”. It is very recognizable with its black and white head, orange or red rounded body with 13 black spots. Both larvae and adults consume enormous quantities of small insects and soft-bodied arthropods, e.g., aphids, whitefly, scale, and the eggs of many insects. The adult females lay their eggs (approximately 30) on a leaf or stem close to a food source (i.e. an insect cluster). One female can lay up to 500 eggs in her lifetime (just a few months). The small yellow eggs will hatch into larvae that are black with orange spots. The larvae immediately begin feeding on the nearby insects. The larvae will continue feeding as they molt and grow, eventually reaching their pupa stage at which point they form a spiny cocoon. They will remain at this stage for a period of up to twelve days depending on climate. The adults will emerge from the cocoon and begin feeding and mating. Lady Beetles have few predators (the lacewing larvae will prey on larvae) and hibernate over Winter.  If purchased, only adults will be shipped. They will be pre-fed, but they will be thirsty so provide them with available water so they will stop and drink and not fly away in search of water.

Green Lacewings
Green Lacewings are appropriately named for their appearance. They are about ½ inches long with large clear green-veined wings. They have gold-ish eyes and long thread-like antennae. The larvae, known as “aphid lions”, will feed on soft-bodied insects, including aphids, leafhoppers, spider mites, thrips, and many insect eggs and larva, especially caterpillars, but the adults only feed on honeydew, nectar, and pollen. The adult females will lay oval shaped pale green eggs (up to 200 in her life span) where insectary plants are present. The eggs are laid at the end of long white stalks on the underside of leaves. The larvae will hatch in just a few days and will search plants for prey. The larvae can be identified by their large hooked jaws, yellowish-grey (or brown) bodies, and are slightly less than ½ inch long. The larvae will continue feeding for 2 – 3 weeks before spinning a white colored cocoon and pupating, usually on the underside of a leaf. The adults, approximately ¾ inch in length, will emerge in about five days and have a life span of about six weeks. During the adult stage, they will mate and start the cycle over. During warm climate, the egg to adult transition can increase. If purchased, the lacewings are sent as hatching eggs/larvae and are generally shipped with a food source, but shipments should be timed so they can be released upon arrival.

• Chrysoperla carnea – for field crops
• Chrysoperla Comanche – for vineyard
• Chrysoperla rufilabris – for trees

Aphid Predatory Midge (Aphidoletes aphidimyza)
The small orange larvae of this insect inject a paralyzing toxin into aphids then suck the body fluids leaving a shriveled skin. The adult is a small, fragile fly (1/16” long) that lays its eggs among aphid colonies at night. Females live about 10 days and can lay up to 250 eggs. Adults will begin to emerge within a week if kept at room temperature (70°F / 21°C). Some insecticides (e.g. insecticidal soap) will kill these predators! Release the midges when aphids begin to colonize. The midges will over-winter in greenhouses if the plant substrate is not changed and no harmful disinfectants are used.

Apple Orchards: Introduce 3 – 5 midges per tree when aphids first appear (early May to mid-June). Repeat if cold or windy weather occurs during initial release period.

Greenhouse Peppers/Tomatoes: Use 1 midge per 2 pepper plants, 1 midge per 6 tomato plants, weekly for 2 – 4 weeks early in season. Repeat if aphids reappear later in the season.

Home Greenhouse or Garden: 2 – 3 releases of 420 midges at 2-week intervals will cover 400 sq. ft.

Mealybug Destroyer (Cryptolaemus montrouzieri)
The Mealybug Destroyer is a species of lady beetle. The adult is small, measuring 3 – 4 mm (1/6 inch) long and is mostly dark brown or blackish with an orangish head and tail. The larvae grow to be much larger, measuring 13 mm and are white with wax-like curls making it difficult to see their legs. Larvae resemble mealybugs except that they are larger and more active. The wax can be scraped off larvae to reveal the pale, alligator-shaped beetle larvae.

Both larvae and adults consume mealybugs. They will also eat aphids, whitefly, armored scales, and soft scales when mealybugs are not present. They are most effective on high populations of mealybugs and at temperatures of 70° – 80° F. The adult females can lay 200 – 700 eggs during their 27 – 70 day lifespan. Females have dark brown forelegs and males have light brown forelegs. C. montrouzieri eggs are yellow and are laid among the cottony egg sacks of mealybugs. Pupation occurs in sheltered places on stems or other substrate. The mealybug destroyer undergoes complete metamorphosis and has about 4 generations per year. Mealybug eggs and larvae are the preferred food for both the adults and larvae of the C. montrouzieri. C. montrouzieri does not survive very well in cold weather and in some situations (orchards, vineyards, and greenhouses) adults are bought and released in the spring in order to establish populations.

Predatory Mites
These predators feed on a wide range of spider mites, both immatures and adults. When a spider mite population can be estimated (using a mite brushing machine or other techniques) introduce 1 Predatory Mite per 25 pest mites, OR if it can’t be determined the number of pest mites, introduce 2 Predatory Mites per infected plant, OR 1,000 – 30,000 Predatory Mites per acre. Greenhouse rate is 1 predator per sq. ft. of planted area plus 10 predators per mite-infested leaf. Release when pest mites first appear. Even distribution is critical, especially on crops like tomatoes where fine stem hairs hamper movement. When webbing is present or pest mite populations are high, reducing the population is recommended with an application of insecticidal oil or insecticidal soap before releasing the Predator Mites. Sulfur dust has been known to kill Predatory Mites in North Coast vineyards. Predatory Mites are shipped mixed-in with a food supply and a granular matrix, which can be distributed from a shaker bottle directly onto infested plants.

• Galendromus (= Metaseiulus) occidentalis needs 50+% relative humidity. This California native is tolerant to Guthion®, closely related organophosphates, and carbaryl (Sevin®). This species of Predatory Mite is recommended for hot greenhouses, tomatoes (for russet mite), grape vines, almonds, and interiorscapes.
• Mesoseiulus (= Phytoseiulus) longipes is similar to persimilis, handles temperatures up to 100°F, tolerates 40% humidity at 70°F (requires more moisture as temperature increases). They are recommended for warm greenhouses, interiorscapes with artificial lighting.
• Neoseiulus (= Amblyseius) californicus is recommended for low-density spider mite populations as it is a slower feeder. Needs a minimum of 60% relative humidity and can tolerate temperatures up to 90°F. They are recommended for greenhouses, corn, berries, ornamentals, and interiorscapes.
• Phytoseiulus persimilis needs 60 – 90% relative humidity. Slightly larger than spider mites, this active orange predator eats 20 young or 5 adult spider mites per day (and often runs out of food). If mites reinfest, it is recommended to release persimilis every 3 – 5 weeks or introduce occidentalis or californicus at same time or two weeks following persimilis introduction. They are recommended for greenhouses, interiorscapes, and field strawberries in coastal areas.

Whitefly Parasite (Encarsia formosa)
This tiny parasitic wasp attacks the 2nd & 3rd instar (scale stage) of the Greenhouse/Glasshouse whitefly (Trialeurodes vaporiorum) and the Sweetpotato/Silverleaf whitefly (Bemisia tabaci). (Please note that this parasite will not control Ash whitefly). Once the whitefly has been parasitized, it turns a black color. As a result, within a very short time it is visibly possible to monitor the progress against them. If the average temperature is less than 70°F, this parasite will not out-breed the whitefly. Higher release rates are often needed in cool pockets of greenhouses (such as in front of evaporative coolers). Parasites are shipped as parasitized scale which are attached to cards that can be hung on plants in the greenhouse. The small cards can be separated at the perforations and distributed evenly through the greenhouse, putting more in areas with the highest whitefly infestations. Greenhouse applications: For low populations (1 whitefly per 5 or more plants), release 1 parasite per plant. For high populations (>1 whitefly per 5 plants), release 5 parasites per plant. It is best to release at least 2 parasites per square feet of whitefly infested areas. Repeat releases 3 more times at two-week intervals for a total of 4 releases. It is best to begin introducing the parasites as soon as whiteflies are seen or at times when they normally are present, preferably when 2nd or 3rd instars are present.

Thrips Predatory Mites  (Neoseiulus (=Amblyseius) cucumeris)
This very tiny (western flower and onion thrips. When thrips populations decrease, this predator will stay alive by eating pollen, leaf surface fungi, and spider mite nymphs. Prefers high humidity. Most pesticides will kill cucumeris. Greenhouse: Use 50 – 100 predators/plant every 1 – 2 weeks until % of leaves with predators equals % of leaves infested with thrips. Introduce late Feb. – Sept. as soon as thrips appear (when plants are small and thrips pop. low).

Parasitic Wasps
These species of wasps (of which there are thousands in the world) lay their eggs in or on a host. When the larvae hatch, they begin eating the host that eventually dies. When the host dies, the larvae then spin a cocoon and pupate into adults. Adults generally feed on nectar from flowers. The following species are some that are specific to agricultural applications.

•    Muscidifurax zarator and M. raptorellus: These tiny parasitic wasps attack the pupae of filth-breeding flies; e.g. house flies (Musca domestica), blow flies or blue-bottles (Calliphorid sp or Phaenicia sp.), little house flies (Fannia canncularis), stable flies (Stomoxys calcitrans), false stable flies (Muscina stabulans), and black garbage flies (Ophrya sp.). Introduce 10 parasites per square foot of breeding area, or based on animal size: 1,000 wasps per large animal (horse, cow); 500 – 725 per small to medium-sized animal (goats, sheep); 10 per head of poultry. It is best to introduce the wasps as soon as adult flies appear. Continue every 2 weeks through the first frost. If introduction is not begun early, then 2 – 3 times the number should be released during the first 2 releases. To improve the control of flies, parasite release should be combined with a manure management program (dry out the manure ASAP to minimize fly egg laying) and adult trapping. Plan to introduce the wasps as soon as they are received as they do not store well.
•   Trichogramma: These very tiny parasitic wasps attack the egg stage of many different moths and butterflies. Timing the releases to target peak egg-laying periods by pest moths and butterflies can be accomplished with pest pheromone traps and field inspection. As a general guideline, weekly releases for 4 – 6 weeks to combat each of the egg-laying periods during the life cycle of the pests. The wasps are sent as parasitized eggs on cards and should be introduced as soon as received.
  • sp. pretiosum – field and row crops
  • sp. platneri – trees in western United States
    T. platneri is best suited for controlling avocado pests and codling moth.
    

Syrphid Flies A.K.A. Flower/Hover Flies (Syrphidae)
Syrphid flies, also known as Flower flies or Hover flies, are usually found where aphids are present. As their common name suggests, the adults can be seen hovering or nectaring above flowers. Their appearance is similar to a tiny bee in that they are black and yellow. The Syrphid larvae can consume one aphid per minute.

Praying Mantids (Tenodera)
We only recommend their use for science projects, to introduce the wonder of insects to children. They eat whatever they run into including other beneficial insects. They are not an effective biocontrol agent for specific problems like aphids or scale.

Bio-Rational Pesticides (BioPesticides)

Bio-rational pesticides were developed in response to the increasing concerns over the undesirable ecological impacts of the conventional/synthetic/petro-chemical pesticides of the post World War II era. Biorationals are considered to have low ecological impacts to the environment. The major categories of bio-rational pesticides include microbial, bio-chemical (derived from a biological source), botanical, insecticidal, and mineral materials.

The advantages of using bio-pesticides include:

• They are usually less harmful than conventional pesticides.
• They generally affect only the target pest and closely related organisms, in contrast to broad-spectrum, conventional pesticides that may affect organisms as different as birds, fish, insects, and mammals.
• They are often effective in very small quantities and often decompose quickly, thereby resulting in lower exposures and largely avoiding the pollution problems caused by conventional pesticides.
• When used as a component of integrated pest management (IPM) programs, biopesticides can greatly decrease the use of harsher pesticides while crop yields remain high.

To use biopesticides effectively, however, users need to know a great deal about managing pests. Some guidance on specific types of biopesticides is provided in the following sections.

It is important to look for these symbols on the product label when selecting pesticides for “Organic” application.

Microbial Pesticides

These pesticides contain a microorganism (e.g., a bacterium, fungus, virus, or protozoan) as the active ingredient. Microbial pesticides can control many different kinds of pests. However, each particular active ingredient is relatively specific for a particular target pest. For example, there are bacteria that control certain fungi, and other bacteria that kill a specific insect or insects at a particular “instar” (developmental stage).

Bacillus amyloliquefaciens

This is a root-colonizing bacterium that is applied to combat some root pathogens like Fusarium, Verticillum, Pythium, Rhizoctonia, Scelrotina, Ralstonia and Phytophthora. It also is effective against leaf diseases such as Powdery Mildew, Downey Mildew, Botrytis, Early and Late Blight, Rusts, Brown Spot and Alternaria. Bacillus amyloliquefaciens releases lipopeptides that kills pathogens by disrupting cell walls of the pathogen. In addition, it also may prevent infection by out-competing pathogens within the rhizosphere. Studies have shown that it can also improve root tolerance to high salt concentrations in the soil.

Bacillus pumulus

This is a bacterium that is applied to combat fungi pathogens. The strain QST 2808 is an aggressive strain of bacterium against Downy and Powdery Mildew as well as rust.  Bacillus pumilus (Bp) produces an antifungal amino sugar compound that affects the fungus cell metabolism.  On plant surfaces, Bp continues to inhibit pathogens from establishing a colony and makes it difficult for pathogens to develop a resistance. It is an excellent combatant where an infestation has occurred. Althgough Bp is a very effective preventative, Bacillus subtilis QST 713 is more cost effective.

Bacillus subtilis
This is a bacterium that is applied to combat fungi pathogens. One strain (QST 713) has been developed as a foliar application to combat Downey and Powdery Mildew and other leaf/bark bearing fungal pathogens like Botrytis. This same strain is also formulated to be applied to the soil and is effective in combating soil-born fungus pathogens like Rhizoctonia, Pythium, and Fusarium. Strain QST 713 is best used as a deterrent against these pathogens.

Bacillus thuringiensis (Bt)
Bt is a naturally occurring, soil-dwelling bacterium used as a biological pesticide. It is a narrow-range, pest-specific insecticide with different strains targeting larvae of different pests including: caterpillars, mosquitoes, black fly larvae and fungus gnats. Once it is ingested, the target insects quickly stop feeding and generally die of starvation within a few days. The major advantage of Bt over broad spectrum insecticides is that it does not kill the target pest’s natural enemies (predators and parasites) and pollinators like honey bees. It is considered safe to people, animals and other non-target organisms. Bt is broken down by sunlight, and persists on foliage for less than a week.

• var. israelensis (Bti): This strain of Bt is effective against larvae of mosquitoes, black flies, and fungus gnats. For mosquitoes and black flies, it is applied to standing water in a granular form. Use to control mosquito larvae in troughs, old tires, rain gutters and ponds. It is safe for use in fish habitats. For fungus gnats, it is applied to the soil or potting medium as granules or as a soil drench.
• var. kurstaki (Btk): This is the most common Bt and it controls a wide array of leaf feeding caterpillars including common garden pests like cabbage worms, budworms, gypsy moth, tomato hornworm, green worm loopers, tent caterpillars, bagworms, sod webworms and oak moths. It is not effective on caterpillars that feed primarily inside plant tissue such as codling moth, fruit tree borers and corn earworm. It is most effective when caterpillars are in 2nd to 3rd instars, when they are smaller and are eating voraciously. NOTE: Proper identification is critical as Btk is only effective on caterpillars; the larval form of butterflies and moths. Sawfly larvae are often confused with caterpillars, but are not controlled by Btk.
• var. tenebrionis (Btt): This strain is toxic to certain beetles. It is commonly used to control Colorado potato beetle and elm leaf beetle adults and larvae, but are not pathogenic or toxic to some other key beetle pests.

Beauveria bassiana
This is a naturally occurring fungus that grows in soil throughout the world. It acts as a parasite on various species of arthropods (aphids, ants, termites, etc.) causing a white “muscardine” disease. This disease is associated with inactivity, disruption of the digestive system, and ultimately cessation of eating. As the insect dies, its body hardens and is then covered by the fungus. When a pupa is infected, it will often be mummified by the fungus.

Cydia pomonella Granulovirus (CpGv)
This is a virus that is naturally occurring in the environment and attacks several invertebrates including Codling Moths. It is highly effective and fast acting on larvae once ingested by the larvae (the larvae must ingest the virus to become infected). Once ingested, the virus begins to multiply ultimately killing the larvae. When dead, the larvae dissolves and releases the virus into the environment where it will be ingested by another larvae. Thorough spraying is a key factor. Resistance to the virus can occur, so regulating its use and incorporating mating disruption, destroying infected fruit, and controlling over-wintering larvae with nematodes is an important part of using CpGv. This virus is non-toxic to humans or other animals.

Gliocladium virens GL-21
This naturally occurring, non-phytotoxic soil fungus is an antagonist to plant pathogenic fungi such as Pythium and Rhizoctonia. It is also effective against Fusarium, Theilaviopsis, Sclerotinia and Sclerotium. It is best used as a preventative by incorporating it into the back-fill mix when planting, or integrating it into the growing media for greenhouse production.

Nematodes – Entomopathogenic
Nematodes are classified as a microbial insecticide because it is considered a microbe. They are the most numerous multicellular animals on earth. A handful of soil may contain thousands of these microscopic worms, many of them parasites of insects (entomopathogenic), plants, or animals. Free-living species are abundant, including nematodes that feed on bacteria, fungi, and other nematodes.

• Steinernema feltiae: Combines ambusher and cruiser strategies and attacks immature fly larvae (dipterous insects) including grubs, mushroom flies, fungus gnats, crane flies, fleas, termites, and more. Maintains infectivity at low soil temperatures, even below 50°F.
• Steinernama carpocapsae: An ambusher type of nematode, best for insects near soil surface like fleas, fungus gnats, fly larvae, ants, termites, webworms, and more. Best used when soil is 72 – 85°F. (55° – 85°F OK) and insect pest is in larval or pupal stage.

Nosema locustae
Nosema locustae is a naturally occurring microsporidial parasitic protosoan which affects only grasshoppers (58 species) and some crickets, by infecting their fat bodies. It will not harm humans, pets, barnyard animals or wildlife, other non-target organisms or the environment. Mortality is greatest to young grasshoppers so the material is best applied before grasshoppers become adults. It takes 2 – 3 weeks for significant death to occur. Grasshoppers are notorious cannibals so they will devour the sick grasshoppers and spread the infection. When females lay eggs they will pass the disease into their next generation. As the eggs hatch, the young hoppers will contract the disease and in this manner at least 15% carryover of the disease occurs. Heavy infestations may make it necessary to apply more than once, or in greater amounts. This is not a contact insecticide; bait must be eaten to be effective. Apply the bait where you see the hoppers eating and feeding, in early spring as soon as the first hoppers are seen. Apply 1 lb. per acre.

Streptomyces lydicus
This is a biological fungus control for soil-born root rot and damping-off fungi. This microorganism colonizes the root system of plants, protecting the plant from Fusarium, Pythium, Rhizoctonia, Phytophthora, and other root-decay fungi. Incorporate into nursery and greenhouse potting soil or growing media. It may also be top-dressed on turf or incorporated into beds, and is often used as a foliar to control and suppress Grey Mold, Brown Patch, and Powdery Mildew.

Trichoderma harzianum
This is a fungus that also acts as a fungicide. It is used as a soil treatment for root protection, a foliar for leaf protection, and as a seed protectant against fungal pathogens.

Bio-Chemical Pesticides

Bio-chemical pesticides are materials derived from naturally occurring substances in the environment (plant, bacteria, or minerals): roots, leaves, seeds or flowers that have insecticidal and fungicidal properties. While these materials are for the most part safer to the user and the environment than chemical-based materials, they are still broad spectrum in nature (i.e., they may kill non-target organisms). The main advantage of their use is they are short-lived in the environment, being broken down into harmless by-products by UV rays from sunlight. The toxic residues from these materials last only 2 – 3 hours to several weeks depending on the material and crop being protected. Biochemical pesticides have the following qualities:

• naturally-occurring substances or structurally-similar and functionally identical to a naturally-occurring substance;
  
• a history of exposure to humans and the environment demonstrating minimal toxicity, or in the case of synthetically-derived biochemical pesticides, is equivalent to a naturally-occurring substance that has such a history; and
  
• a non-toxic mode of action to the target pest(s).

Bio-chemical pesticides include, but are not limited to: natural plant and insect regulators; naturally-occurring repellents and attractants; insect pheromones and kairomones; and enzymes.

Spinosad(Saccharoployspora spinosa)
This pesticide resulted from observations of a Caribbean soil sample found to be active on mosquito larvae. The microorganism, Saccharopolyspora spinosa, was isolated from the soil sample, and the insecticidal property of the spinosyns was identified. Most of the insecticidal activity is due to a mixture of spinosyns A and D, commonly referred to as spinosad. Insects that are exposed to spinosad exhibit classic symptoms of neurotoxicity: lack of coordination, prostration, tremors, and other involuntary muscle contractions leading to paralysis and death. Although the mode of action of spinosad is not fully understood, it appears to affect neuroreceptor function through a novel mechanism. Spinosad presents a favorable environmental profile. It does not leach, bio-accumulate, volatilize, or persist in the environment. Spinosad will degrade photochemically when exposed to light after application. Because spinosad strongly adsorbs to most soils, it does not leach through soil to groundwater. Spinosad demonstrates low mammalian and avian toxicity. No long-term health problems were noted in mammals, and a low potential for acute toxicity exists due to low oral, dermal, and inhalation toxicity. This is advantageous, because low mammalian toxicity imparts reduced risk to those who handle, mix, and apply the product. Although spinosad is moderately toxic to fish, this toxicity represents a reduced risk to fish when compared with many synthetic insecticides currently in use. Spinosad has proven effective in controlling many chewing insect pests in cotton, trees, fruits, vegetables, turf, and ornamentals. High selectivity is also observed: 70 – 90% of beneficial insects and predatory wasps are left unharmed.

Botanical Pesticides

Botanical pesticides are derived from plants. Botanicals are generally short-lived and break down fairly rapidly in the presence of UV light and air. As a result, they do not provide control for more than a day to several days. They are generally only moderately toxic to wildlife (and humans), but they can be irritating to the mucous membranes. Many of the newer botanicals have low toxicity to mammals. It is always important to read the label for “Cautions,” “Warnings,” and “Directions of Use” for any pesticide before application.

Azadirachtin
Azardirachtin is a secondary extract of the neem tree seed oil that has been used for thousands of years as a pesticide. It deters some insects from feeding, but is usually applied to inhibit the normal life cycle of insects (e.g., molting, mating and egg laying). It is considered a broad spectrum pesticide, which means that it will affect all insects, including beneficials, so it should be applied in the early evening. It has a classification of “relatively non-toxic” to humans. It can be used as a soil drench for soil-borne insect larvae. Safe for use on vegetables, fruit, in greenhouses and hydroponics. It is not a quick-kill but a longer lasting protection against pest infestations. Residual activity is present on leaves for 7-10 days. It can be used as a preventative. Azadirachtin biodegrades in the environment. (Also see Neem)

Corn Gluten
Corn Gluten is an herbicide that gives acceptable pre­emergent control of annual bluegrass, black nightshade, buckhorn plantain, catchweed bedstraw, common lambsquarter, clover, crabgrass, creeping bentgrass, curly dock, dandelion, giant foxtail, orchardgrass, purslane, and redroot pigweed. Corn gluten meal inhibits the establishment of germinating plants by preventing root formation through an enzymatic reaction. It works best when applied 2 weeks before weed germination (usually spring and fall). This powdered material is easy to apply through a drop spreader followed by a water application. When weeds have germinated, allow for a drying out period for the affected plants to die off (since they have little or no roots) before irrigation is resumed. Do not apply to newly seeded or overseeded lawns or vegetable gardens. In replicated field research, crabgrass was reduced by 58% the first year, 85% by the second year and 91% by the third year. It also provides 9% nitrogen, 1% phosphorus by weight as a slow-release fertilizer. This food-grade product is not toxic to people, pets or wildlife.

d-Limonene
This is a terpene extract of citrus peel oil. It is a broad spectrum contact pesticide that is used against ants, roaches, palmetto bugs, fleas, silverfish and many other insects including mosquito larvae. It destroys the wax coating of the insect’s respiratory system which causes the insect to suffocate. d-Limonene dissipates relatively quickly so it does not have any residual impact. It has a low toxicity classification for mammals, birds, and fish but it can cause skin and respiratory irritation. d-Limonene has also been found to be very effective as a weed suppressant or “knock-down.” It destroys the cell wall and chloroplasts of leaves. It is not a systemic herbicide that “kills” the plant; it only destroys the foliage.

Melaleuca alternifolia (Narrow-leaved Paperbark, Narrow-leaved Tea-tree)
The extract of this plant is a broad-spectrum fungicide and bactericide with prophylactic and curative properties. It has been found to be effective against a broad range of Oomycetes (water molds) and Ascomycota (sac fungi) including Downy and Powdery Mildew, Botrytis cinerea, Early blight, Rust, and more.

Neem
A naturally occurring pesticide made from the seed of the Neem tree. It offers broad spectrum fungicide, insecticide and miticide control. Used as a fungicide for control of foliar plant diseases including Anthracnose, Alternaria, black spot, Botrytis, downy and powdery mildews, rusts and scab. Neem oils protect plant tissues from infection and will kill fungi on contact. As an insecticide, neem oils control eggs, larval and adult stages of aphids, beetles, leafminers, leafhoppers, leafrollers, mealybugs, rust mites and spider mites, scales, thrips, and whiteflies. As an oil, it can smother all life stages, and acts as a repellent. It also interferes with insect hormones, interrupting feeding and mating. It is not an instant kill, rather a multi-modal treatment that reduces insect populations. Insect repellency lasts up to several weeks until weather degrades it or plant growth forms new untreated tissue. Spray injury may occur to plants under drought stress and when oils are applied when temperatures are over 80°F . Follow special directions if the air or water temperature falls below 55°F. To minimize impact to bees, other pollinators and beneficial insects, spray in the early evening. (Also see Azadirachtin)

Pyrethrum/Pyrethrin
Pyrethrum is derived from crushed, dried flowers of Chrysanthemum cineraifolium, a perennial daisy family plant grown in Kenya. Pyrethrum quickly dissipates and is rendered inactive by UV rays within 24 hours after application. For this reason, it is recommended that it be applied late in the day, preferably after sunset, to allow the botanical as long a time as possible to work on the pests. Pyrethrum works as both a contact and stomach poison for insects. It is a broad spectrum insecticide that is often used against greenhouse pests, houseflies, fruit flies, fleas, ticks, lice, silverfish, and ants. NOTE: Do not confuse this product with the synthetic pyrethroids, which are man-made, have long residuals and are highly toxic to beneficial insects.

Quillaja Saponaria Saponins
The extracted saponins of the whole biomass of the Quillaja Saponaria tree have proven to be very effective against plant parasitic nematodes. The exact mode of action is under study but is not yet understood. These extracted saponins are considered to have relatively low toxicity to humans and the environment.

Reynoutria sachalinensis – Extract of
This extract of the Giant Knotweed is highly effective as a preventative treatment for powdery mildew, downy mildew, Botrytis grey mold, Early blight, Late blight, and Bacterial leaf spot. It can be used on many edibles and ornamentals. When sprayed on plants, this extract encourages the plants to activate and internal defense system that prevents the growth of these mildews and grey molds. It can be used as a foliar, soil drench, plant dip, or applied through a drip irrigation system. This extract is not known to cause any adverse affects on the environment or humans.

Rotenone
Rotenone is a rotenoid plant extract derived from the roots, seeds, and leaves of barbasco, cub, haiari, nekoe, and timbo members of the pea family. Rotenone is a selective, non-specific insecticide with some killing properties for mites and ticks. Rotenone is used in home gardens for insect control, for lice and tick control on pets, and for fish eradications as part of water body management. Research has shown that, in addition to fish and fowl, it can have adverse toxic effects on humans and other mammals (kidney, liver, digestive, respiratory, and dermal effects). Rotenone is non-toxic to bees except when used in combination with Pyrethrum/Pyrethrin. It breaks down quickly in soil and in water within 2 – 6 days depending on sunlight, and it does not leach from soil.

Ryania
Ryania is derived from the ground stems of Ryania speciosa, a native plant of the tropical regions of the Americas. Ryania is highly toxic to the fruit moth, codling moth, corn earworm, European corn borer, and citrus thrips, but it is ineffective against the cabbage maggot, cauliflower worms or boll weevil. Ryania has a very low toxicity to mammals and is labeled with the CAUTION signal word. At high doses, it affects muscles by preventing contractions and resulting in paralysis. Symptoms of poisoning include vomiting, weakness and diarrhea. Rigidity of the muscles and depression of the central nervous system can lead to a coma and to death. Ryania is moderately toxic to birds and wildfowl. Ryania is one of the oldest botanical pesticides, but it is rarely used.

Sabadilla
An extract of South American lilies, Sabadilla is a broad spectrum contact insecticide with ingestion poisoning qualities. It is most effective against “true” bugs (harlequin bugs and squash bugs). Sabadilla degrades quickly in air and sunlight with no lingering effects. It is extremely toxic to honey bees, but the least toxic botanical pesticide to humans. Sabadilla was one of the first botanical pesticides but is now rarely used.

Oils – Botanical
Various oils have been extracted and used for non-specific target pests. Many oils are also used as fungicides and for weed suppression.

• Clove, Garlic, Cottonseed & Canola Oils are broad spectrum contact insecticides which block insect-specific neural pathways that don’t exist in mammals or birds. Mortality can occur within minutes of application but may take hours depending on the type of insect pest and the concentration of product that contacts the insect directly. Controls a wide range of insects including ants, aphids, beetles, caterpillars, centipedes, crickets, cockroaches, earwigs, firebrats, fleas, flies, gnats, grasshoppers, mealybugs, millipedes, mosquitoes, pillbugs, sowbugs, scale, silverfish, spiders, ticks, whiteflies and other insect pests.
• Capsaicin Oil is used to repel aphids, thrips, mites, leafminers, leafhoppers, scale, whiteflies and some foliar feeding caterpillars. Derived from hot peppers, the active ingredient is capsaicin, which is an irritant that can keep pests off of treated plants. Capsaicin is also used as a repellant for skunks, raccoons, rabbits, dogs, and cats due to its pepper aroma.
• Sesame Oil Kills the eggs, larvae and nymphs of insects and the adult stage of over 25 soft bodied insects including aphids, citrus rust mites, leaf rollers, mealy bugs, scale insects, spider mites, thrips, whiteflies and hemlock wooly adelgid and more. Also controls certain fungal diseases such as powdery mildew, black spot on roses, helminthosporium and citrus greasy spot among others.

Oils – Paraffinic/Mineral/Petroleum

Oils have been used as pesticides for hundreds of years and have been some of the most effective and safe alternatives to petro-chemical insecticides and fungicides.Petroleum oils are highly refined Paraffinic Oil that are used to control many plant pests and diseases. They are also commonly called Horticultural Oil or Mineral Oil and have been approved as an “organic” control of fungus, insects, and arachnids. The oil is a broad spectrum pesticide that essentially suffocates the pest. Modern, petroleum-based horticultural oils are refined to standard specifications. The unsulfonated residue (UR) is a measure of the degree of oil refinement and is expressed as a percentage. Oils contain saturated and unsaturated hydrocarbons. Saturated hydrocarbons are more stable than unsaturated hydrocarbons, which can form toxic substances when sprayed on plants. In general, the higher the UR, the less unsaturated hydrocarbon content in the oil and the less likelihood of plant injury. Dormant oils have UR between 50-90 percent; summer oils, between 92-96 percent. Stylet oils are highly refined horticultural oils and have UR above 99 percent. Viscosity is a measure of oil “thickness” and is expressed in time units (Saybolt seconds) required for the oil to flow through an opening of standard size. In general, the lower the viscosity, the less likelihood for plant injury. The viscosity of horticultural oils varies between 60-90. Distillation range is a measure of the purity of the oil fraction and is expressed as a temperature range. The temperature range represents the boiling point of the oil components at 10 and 90 percent distillation. In general, the more narrow the distillation range, the more predictable the performance of the oil when sprayed on plants. Distillation ranges of 80°F or less are considered “narrow range” appropriate for spray oils. Oils with boiling points above 455°F may damage plant foliage. Minimum and maximum boiling points of horticultural oils vary between 412°F and 468°F, depending on the type of oil.

Insecticidal Soaps

Insecticidal soaps are specially formulated materials generally derived from plant or animal materials that contain potassium or sodium salts of fatty acids. They are some of the earliest and most widely adopted “organic” insecticides because of their low toxicity to humans, pets, and many beneficial insects. Insecticidal soaps are one of the safest choices available for controlling pests on the farm, in the garden, or in the home. They control adelgids, aphids, mealybugs, whiteflies, mites, and other pests. Insecticidal soaps are a contact insecticide, so the solution must completely coat the pest. Once the liquid has dried, it becomes ineffective so the insects are not harmed even if they walk over it. For example, spraying only the upper surface of the leaf will probably not affect whiteflies since they usually feed on the undersurface of leaves. Immature stages of the whitefly don’t move very much and will not be affected unless the liquid is applied to the underside of the leaf. Only apply soaps when and where an infestation appears, not as a preventive measure. Once you find the pest, treat only the infested plants. Watch for any adverse plant reaction, or injury, from the treatment, and do not apply to plants that are under stress (drought being the most common cause of stress). Adverse reactions on the foliage could appear as yellow or brown spotting, “burned” tips, and yellow or brown scorching on leaf edges. Soaps may also cause marking on certain apple, pear, and stone fruit varieties. Adverse plant reaction is the most common concern when using insecticidal soap.  Another consideration is the water in which the soap is mixed. “Hard” or alkaline water can reduce the efficacy of insecticidal soaps. If the alkalinity of the water is not known, a simple test can be performed by putting a small amount of the insecticidal soap (at normal dilution) in a jar of water and shake to see if it creates foam. If no foam appears, more than likely the water is “hard” or alkaline. If so, a kit can be used to reduce the effect the water’s magnesium or calcium has on “locking up” the potassium salts.

Mineral Pesticides

These pesticides are derived from natural minerals that generally are mined or are a by-product of mining. Each mineral pesticide is typically specific to a class of pest.

Boric/Orthoboric Acid/Borax
Boric acid, also known as orthoboric acid or borate, is a low-toxicity mineral that possesses insecticidal, fungicidal, and herbicidal properties. It does not evaporate or volatilize into the air, but it can still pose health hazards and should be used with care. While boric acid is somewhat slower acting than the petro-chemical pesticides, it is highly effective over a long period of time. It is most often used as an insecticide for ants, termites, cockroaches, and weevils, but it also possesses fungicidal applications for citrus. As an insecticide, boric acid acts as a stomach poison on insects that eat the treated medium/material, but it also acts as an abrasive on crawling insects’ exoskeletons. Boric acid does have phyto-toxic properties that interrupt photosynthesis in plants. Boric acid also has moderately toxic effects on mammals, so it is important (as with all pesticides) to read the label and instructions carefully.

Copper
There are many forms and compounds of copper available to organic gardeners and farmers. Each has a specific target pest or class of pest. It is effective against many different fungal and bacterial plant diseases. Copper is commonly used as a dormant season spray, but it is also applied during the growing season if appropriate. It is generally considered safe and effective, but tissue damage can occur if used on sensitive plants or in excess of label directions, so it is important to read the label and apply it carefully. In general, most pesticides containing copper are registered for peach leaf curl, shothole fungus, apple scab, brown rot, powdery mildew, early and late blight of tomatoes, citrus fungi, and other diseases. Repeated annual applications can result in a buildup in the underlying soil which can be detrimental to soil biology, and present a risk of run-off. There is no evidence that copper compounds are acutely toxic to humans or other mammals, but it is highly toxic to fish and aquatic invertebrates. Additionally, there is no evidence that it is toxic to bees or other beneficial insects.

• Copper Oxychloride is a broad-spectrum control of a wide range of fungal and bacterial diseases
  (see above).
• Copper Hydroxide is a broad-spectrum control of a wide range of fungal and bacterial diseases
  (see above).
• Copper Ammonium Complex is a broad-spectrum control of a wide range of fungal and bacterial diseases (see above).

Diatomaceous Earth
Diatomaceous Earth is the ground-up fossilized remains of one-celled fresh water algae called diatoms. Diatomaceous Earth kills in two ways: 1) It pierces the skin of insects traveling through it, and 2) It punctures the internal organs of those eating it. It is most effective under dry conditions. DE can be applied as a dust, a wettable powder, or as a barrier to crawling insects such as ants, termites, and earwigs, as well as slugs and snails. Dusted on damp foliage, it will control soft-bodied insects such as aphids and thrips. It is also used for worm and parasite control as a feed additive for some livestock animals, and also as a stored grain additive at 4 oz. per 100 lb. Use dust mask when applying, to avoid breathing the dust. Apply in early morning. (Note: Insecticidal-grade DE should not be confused with the kind that is sold for swimming pool filters, which has been heat treated and calcined to form a fused product that works well for a filter but has no insecticidal properties.)

Iron Phosphate
Iron phosphate is one of the best products for controlling snails and slugs. It is an organic compound that is found naturally in the soil, so when it breaks down, it also serves as a fertilizer. Its mode of action is against the snail or slug’s digestive system. After it is ingested, it disrupts the metabolizing of calcium causing the snails and slugs to immediately stop eating.

Lime-Sulfur
Lime-Sulfur has been used for many years (since the early 1900’s) as a dormant spray for peach leaf curl, brown rot, and other fungal diseases. It can also be applied to combat pear blister mite, cane blight, and scab in pomme fruit. It is very effective against these pests and breaks down quickly in the environment. In 2008, the EPA requested that it no longer be available for “retail” or “off the shelf” sales. By the end of 2009, the “off the shelf” inventory for less than 2.5 gallons (agricultural use) was gone. It is still available in container sizes from 2.5 gallons and up but requires a Pest Control Applicators License or a Homeowner’s Exemption. Lime-Sulfur does have some adverse environmental affects if applied inappropriately, and is considered toxic to humans and other animals.

Kaolin Clay
Kaolin clay is an edible mineral long used as an anti-caking agent in processed foods. It has not been linked to any mammal toxicity or adverse affects on the environment. Kaolin clay is used predominantly in apple orchards due to its adverse effects on the codling moth. However it is also used in general agriculture and horticulture as a control of leafrollers, leafhoppers, mites, thrips, and many other pests. Reduced fruit drop, heat stress, and sunburn have been identified as additional benefits of applying kaolin clay. Against insects, kaolin clay acts as an irritant and repellant due to its “stickiness,” which causes the insects stress and discomfort. The material also inhibits egg laying by the insects.

Potassium Bicarbonate
Potassium bicarbonate is a naturally occurring compound that acts as a curative fungicide for control of powdery mildew. It works by disrupting the potassium ion balance in the fungus cell, causing the cell wall to collapse and the cell to shrink. It is a contact fungicide so it must have direct contact with the fungus to be effective.

Sulfur
The oldest recorded fungicide, Sulfur is a naturally occurring mineral that is mined in various parts of the world. As a pest control, it is applied to control fungus and molds. It is generally applied at bud break or during damp/moist periods when plants are most susceptible to being attacked by a fungus or mold. Sulfur is also applied as a dust to control mites.

Insect Pheromones, Kairomones, Attractants and Traps

These are compounds produced by living organisms or synthetically derived substances that are structurally similar and functionally identical to naturally-occurring pheromones, which, alone or in combination with other such compounds, modifies the behavior of other individuals of the same species.

A number of pheromone traps have been developed over the years to disrupt the mating cycle of various pests, including the codling moth, whitefly, filbert worm, fruit-tree leafroller, armyworm, cucumber beetle, and many others.

Pest Control Chart

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