A single beetle can consume more than 5,000 aphids during its lifetime. It feeds on aphids, scales, mealybugs, thrips, mites, and insect eggs. It can eat 100 or more insects a day. They're also cannibalistic if food is in short supply. Although they've been observed on field and garden crops, their primary value as predators appears to be controlling harmful meadow and pasture insects such as crickets and grasshoppers.
Dragonflies catch and eat their prey in flight.
Mosquitoes and other flies make up a large part of their diet. They lay eggs in the bodies of other insects, including caterpillars, aphids, thrips, and borers. Once hatched, larvae of parasitic wasps feed on the body fluids of the hosts. Some of the most common of these wasps parasitize tomato hornworms and Mexican bean beetles. They don't sting.