As growers, so much of our time is spent scouting for harmful bugs in the garden that sometimes we neglect the good guys. The truth is, there are lots of insects that can provide valuable services to you, from pollination to pest control. With just a little bit of research to learn what good bugs are out there, and a little bit of patience to wait for them to get to work, you can save yourself time, energy, and money. There are lots of beneficial insects out there, but I'm just going to go over a few of the more common ones today.
Lady beetles are well-known garden friends, because they have a voracious appetite for aphids. As I've written about in a previous post, releasing ladybugs in greenhouses or other enclosed areas is a good way to fight aphids. While their larvae also like to snack on aphids, adult lady beetles can eat up to 50 aphids a day, so you want to make sure you release them in an area with a heavy infestation. It's not a method to use if you have a mild aphid outbreak. Lady beetles also eat pollen and nectar, so inter-planting your vegetable garden with flowers is a good way to attract them naturally. Planting several different kinds of flowers helps ensure a nectar and pollen source over a longer period of time. This may encourage lady beetles to stick around.
There's a great beneficial insect that has a particularly bad reputation due to its mean sting, but wasps also provide a great pest control service. Wasps feed on the bugs that feed on your plants, so think about that next time you want to spray one of their nests! (Side note: if anyone in your household is allergic to stinging insects, or if there is a wasp's nest in an a high-traffic area of your household, I always recommend getting rid of them. Safety first!)
There's another species of wasps called parasitoid wasps, or parasitic wasps, that are probably the creepiest of all beneficial insects. Parasitic wasps feed off of nectar from the plants in your garden, but when it's time for them to make babies, they temporarily paralyze unwitting caterpillars with their venom and lay eggs in or on them. The host caterpillars remain alive while the wasp eggs develop, but when the wasps pupate, they eat their way out of the caterpillar to emerge into the world. The caterpillars are eaten alive. It sounds horrifying, but once you have a few too many Tomato Hornworms destroy your beautiful Brandywines, you'll start to feel less sympathetic! If you've got the stomach for it, you can check out these cool photos of parasitic wasps emerging from caterpillars over at this NC State Extension page. (Side note: you should follow that page anyway, because it's run by Extension Agent Debbie Roos, and she's a genius.)
There are some bugs that are both good and bad. Praying mantises are some of the coolest insects you can find in your garden, but they don't discriminate when it comes to their meals: they'll eat good bugs and bad bugs alike! They'll even eat other mantises if they get hungry enough. Generally, though, they're good for a garden, so I like to keep them around. They're especially great to have around for the hard-to-kill hard-shelled bug infestations like Colorado potato beetles or harlequin beetles. You can even order egg cases online and hatch them into your garden.
Last but not least, pollinators! If you're growing any kind of vegetable, you should definitely be planting flowers to attract pollinators. At my school's farm, we have an entire bed dedicated to perennial flowering plants for pollinators, including milkweed, coneflower, Joe Pye Weed, elderberry, salvia, and more.
Pollinators are essential for ensuring a stable food supply. One third of our agricultural products depends on them! We have over 4,000 species of bees in the United States. Most people know about the plight of our honeybees, but there are dozens of native pollinators with vulnerable populations in rapid decline, too. Planting diverse flowering crops that bloom throughout the growing season is critical for supporting pollinator populations. A diversity of flowers also supports a diverse pollinator population. I love sitting out in the garden and seeing the honeybees, bumble bees, mason bees, sweat bees, beetles, and even flies visiting bloom after bloom.
I also love watching the butterflies in the garden. Many people know that milkweed is essential for monarch butterflies. Attracting other kinds of butterflies is easy. They like nectar sources from flat-topped broad-petaled flowers that they can land on, like zinnias, coneflowers, and dahlias. Planting just a few of those flowers will attract beautiful butterflies throughout the warm seasons. Many butterflies and moths need to warm up before they take flight, so if you head out to your zinnia patch early in the morning, you can often see them soaking up the morning rays on top of the flowers.
Your garden is an ecosystem of all kinds of six-legged critters, and if you plan ahead and have a little bit of patience, you can put the good ones to work for you.
If you're not sure if a bug you're looking at is good or bad, take a look at NC State's great visual guide to beneficial insects here.