Where can I get beneficial insects for my garden?

Got an infestation of aphids, thrips, mealybugs, or whiteflies and you’re not squeamish about small-scale biological warfare? Beneficial insects, also known as “natural enemies,” may be an attractive option for you. Predators and parasitoids of many common garden pests, beneficial insects can consume many times their weight in damaging pests, cleaning up your plants.

Common Insect PESTS (images and info)

If you lived on the mainland, you could purchase a quart of ladybugs, a bottle of lacewing larvae, or a jar of predatory mites! But here in the 50th state, we’re so vulnerable to new pests and diseases that can hitchhike along with these living products, that our quarantine regulations prohibit bringing these animals into our state.

Don’t be discouraged! Many species of beneficial insects are already here in Hawaii and just need to be called to the dinner table. How does the backyard gardener do that?

First, learn who the good guys are. Scout around your garden once or twice a week to see who’s living there now. You may observe predatory insects scuttling quickly after their prey. Beneficial insect identification flashcards for Hawaii are available for free on-line at http://go.hawaii.edu/BR. Be sure to notice what these insect allies look like throughout their life cycle. Like butterflies, they too go through extreme metamorphosis, radically changing their appearance. For example, young ladybeetles (ladybugs) resemble tiny alligators with pinchers, and like most teenagers, they have a voracious appetite -- for aphids, whiteflies, and mealybugs. See if you can spot "aphid mummies" and other signs that pests have been parasitized.

Second, make beneficials feel welcome. These insect allies need food (pollen and nectar), water, and shelter (or “habitat”). Your backyard or garden should offer all of these elements year round for beneficial insects to call it their home. Lure lady beetles, hoverflies, and parasitic wasps by growing rows of buckwheat and cilantro, letting them flower. Minute pirate bugs will enjoy marigold and cosmos. Trichograma wasps relish sunn hemp and cowpea. Use an organic mulch on the soil surface to appeal to predatory spiders. Install a nesting block for key-hole wasps and aphid collecting wasps.

Third, control ants in the garden. Certain ants actually raise and protect herds of aphids, mealybugs, and whiteflies on garden plants, feeding off their sweet secretions called honeydew. Treat trees by wrapping sticky barriers around the trunk (such as Tanglefoot), remembering to check and replace them regularly. Boric acid bait stations placed near ant nests and on trails can also help.

Finally, put away most of your pesticides and reduce your reliance on them. The home garden is a great place to use products with low toxicity to people and animals, products that biodegrade quickly. Horticultural oils, insecticidal soaps, microbial and botanical insecticides meet this need and can be used successfully in the home garden. Look for them in your garden store. Avoid using broad spectrum insecticides such as organophosphates (eg. Malathion), carbamates (eg. Sevin), and pyrethroids (eg. Talstar). Major outbreaks of aphids and scales in the garden are often the result of having used broad spectrum pesticides which kill natural enemies.

Notes

Why isn't praying mantis on our list of beneficial insects? Members of the mantis family are formidable ambush predators but are not very discriminatory about what they eat. Because they will consume large quantities of beneficial insects as well as pests, they were not included on the list.

Will these practices help honey bees? Honey bees will also benefit from improved habitat (nectar, pollen, clean water) and from eliminating the use of broad spectrum pesticides. Even organic pesticides such as neem oil can kill honey bees. Some additional products known as neonicotinoids, found commonly in many products at your garden store have been implicated in disrupting bee health. Learn more about these and other pollinators here.

Are parasitic wasps a threat to the native Kamehameha butterfly? Possibly YES, Trichogrammatidae wasps (considered to be beneficial to gardeners) pose a threat to the Kamehameha butterfly (Vanessa tameamea), endemic to Hawai'i and found nowhere else in the world.

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