Beneficial insects are bugs that eat or otherwise kill bugs that damage crops. Ladybugs are perhaps the most famous beneficial insect — young ladybugs (technically, larvae) in particular are fast-moving, quick-growing ravenous eaters. They eat aphids like teenage boys snarfing down potato chips.
There are other similarly carnivorous insects that help farmers keep pests in check. Green lacewings have offspring that look similar to ladybugs, but their team uniforms have green stripes instead of orange. The Assassin Bug, pictured below in our field about to eat a Spotted Cucumber Beetle, lives up to its name. It eats all manner of
But insects kill each other in more creative ways too. Like the creature in the “Alien” movie, tiny insects like Hover Flies and Aphitus wasps use a probiscus to spear other bugs and insert their eggs inside. When the eggs hatch, the young fly or wasp larvae feed on the insect from the inside and eventually emerge, leaving just a hollow shell behind them. Subscribers with children heading off to college can perhaps identify.
In nature, beneficial insects can keep destructive pests in check. On a farm it’s not so simple. The pests might do significant damage to a crop before the beneficials show up to get things under control. That’s why even on organic farms, safe and relatively benign pesticides are used to keep pest outbreaks from getting out of hand. (It’s critical not to kill beneficials when spraying or you will make the pest problem worse) If the pest populations stay small, the beneficials will keep them small. In general, this concept is known as Integrated Pest Management.
If there are no beneficials feeding on pests in your field, you can buy them online. Depending on the situation, they arrive either as eggs, larvae or adults. While this may help keep pests in check, it has not been shown as an effective way to combat a major infestation — the beneficials simply can’t keep up.
In the last few years, reesearchers have been focusing more on proactive ways to attract beneficials to your farm before the pests get started. While young beneficial insects like ladybugs, lacewings, hoverflies and aphitus wasps eat lots of meat, it turns out their parents have more sophisticated tastes. They line up like college students at an open bar for allsyum, coriander, and other sweet-smelling flowers and fuel up on the nectar. Then they fly off into the surrounding fields, drunk on sugar, to procreate. The more nectar sources near a field, the more adult beneficials that will show up, and the more trips they will make out into the crops to make whoopie and lay their eggs.
After several years of research, UC crop advisors are recommending that vegetable growers plant up to a tenth of their fields in nectar-producing flowers. For the first time, we are planting a small amount of Sweet Allysum in each of our broccoli and cabbage fields at Terra Firma. The allysum is already flowering when we plant it, and I was amazed to see the adult beneficials actually feeding on the nectar while we were planting last week.
As we go into fall, our pretty green fields will be even prettier with rows of flowers every hundred feet. But if you zoom in close, the scene won’t be as pretty, more like an “R” rated horror film with insects playing all the roles. We’ll be cheering for the beneficials.