Kids are fascinated by bugs, but adults want to smash, crush, flush, and spray them. Did you know that about 98 percent of insect species are beneficial? They pollinate crops, loosen the soil, and either eat or parasitize pest insects. We can provide a healthy environment for these little helpers by using organic matter to build up the soil, rotating crops to prevent soil nutrient depletion, and planting at the proper times. By being good hosts to the beneficial insects, spiders, and mites in our garden, we will enable them to manage the pests. When they do their job, we should rarely have to reach for the pesticides.
Lady beetles are a favorite guest in the garden. Industrious predators, they eat aphids, leafhoppers, mites, thrips, scale insects, mealybugs, and insect eggs. There are over 250 endemic species in North America. Other predatory beetles are ground beetles and rove beetles. Ground beetles may prey on slugs, cutworms, earthworms, and other beetles. Rove beetles feed on smaller insects, such as fly maggots, ant larvae, and mites.
Most gardeners are familiar with the praying mantid (mantis). Its dining preferences are flies, wasps, bees, caterpillars, moths, and butterflies. Unfortunately, the bees and butterflies are beneficial.
Lacewings are a sign of a well-balanced, healthy garden as they do not survive pesticides. The larvae are the real workhorses, sucking out the insides of their prey.
Because of its name, the earwig can arouse disgust. Originally from Europe, earwigs may have crawled into ears as people slept on damp ground in the Middle Ages. These omnipresent omnivores are beneficial in the garden in moderation, eating aphids and small caterpillars, as well as flower petals and leaves.
Ant species can be either predatory or honey-dew collectors. Fortunately, the predatory species predominate in the garden, controlling a variety of pests and scavenging. Honey-dew collectors, on the other hand, can act as protectors to pest insects.
The aptly-named stink bug, either predatory or plant-eating, is a familiar predator bug. Our native stink bugs do not cause a problem in the garden, but we have a recent unwelcome invasion of the marmorated Asian stink bug (Brown marmorated stink bug). This plant-eater causes considerable crop damage in fruits and vegetables. Learn to identify it so you won’t encourage it to stay. (The Samurai wasp, a parasitoid, is being used to control this pest, but there will be more about that in a later column.)
Other predator bugs include damsel bugs, big-eyed bugs, assassin bugs, ambush bugs, mirids, and minute pirate bugs.
Even some flies are beneficial. Predatory flies can look like flies or resemble other insects, such as bees, wasps, or mosquitoes. They include hoverflies, bee flies, robber flies, midges, long-legged flies, and dance flies. The adults and larvae feed on a wide variety of small, soft insects.
Centipedes eat cockroaches, spiders, beetles, caterpillars, earthworms, pillbugs, and earwigs. You will find the 2-inch-long stone centipede under pots and stones. Do not handle it, as it will bite. Perhaps they are worth the risk if they eat cockroaches.
Two tiny predators are important in Northwest gardens: thrips and mites. Some thrips can cause minor plant damage, but also eat insects. Other thrips are true predators. Predatory mites are invisible warriors against pest mites, both in the garden and in bio-control programs in agriculture.
Finally, both predator and non-carnivorous insects are pollinators, as are butterflies, honey bees, and the hundreds of native bee species in the PNW. To attract a healthy and diverse insect community, avoid the use of pesticides, minimize lawn areas, and plant more bushes, shrubs, and native plants.
