Beneficial Bugs for your Garden
Emily Ellis
Gardens are made up of so much more than plants. A healthy garden thrives with a wide variety of organisms, and some of its most significant residents are insects – the creepy-crawly critters that pollinate plants, eat and are eaten by other creatures, and generally help keep things up and running.
Of course, balance is key to any ecosystem, and not all insects are good, as anyone who has done battle with pests like aphids and Japanese beetles is well aware. While some insects, like bees, should be widely welcome, some predatory insects, like praying mantises, are beneficial only if they are not putting a dent in your population of other helpful organisms. Scroll below to read our about seven (generally) helpful garden insects found in Northern Virginia, and how to attract them to your property.
Bees
One of Oak Spring’s honey bees.
As a general rule, any type of bee you come across in Northern Virginia is beneficial for your plants (even the slightly annoying ones, like sweat bees and carpenter bees, are good pollinators). Bees as a species – particularly bumble bees and European honey bees, which are essential to the world’s food crops and wild plants – are in a global decline due to climate change, overuse of pesticides, and lack of crop diversity. Fortunately, there are plenty of steps you can take to draw these helpful insects to your property – and know you are doing your part to help boost bee populations.
Learning how to identify the nesting needs and plant preferences of the bees you want in your yard is a good way to start. Our friends at Virginia Working Landscapes have a great infographic of eleven local bumblebee species, including their markings, conservation risk, and favorite flowers. This list from Virginia Tech includes helpful information on lesser-known local bee species, such as mason bees. Generally, planting a variety of native blooms is a good way to attract both native bees and honey bees to your yard.
Another way to help out local bees is by priming parts of your garden for ground-nesting species, such as cellophane bees: about 70% of the world’s 20,000 bee species actually nest in the ground, rather than building hives in trees or buildings. Keeping areas of your property free of mulch, and ensuring the soil there is loose and easy to dig, will make your garden attractive for these ground-dwelling pollinators.
Butterflies
A monarch at Oak Spring. Photo by Sarah Causey
There are 53 butterfly species found in Virginia, and they’re all good for your plants. While butterflies aren’t quite as efficient as bees are at pollinating – they can’t pick up quite as much pollen on their slimmer bodies – they are still very important pollinators, particularly for certain vegetables and herbs. Like bees, butterfly populations worldwide are taking a downturn due to climate change, pesticides, and habitat destruction; black and orange monarch butterflies, once common throughout the United States, are currently at a particular risk, their populations having plummeted more than 80% over the past 20 years.
So what can you do to attract these beautiful pollinators to your yard? For one thing, learn how to identify their caterpillars so you don’t mistake them for a garden pest - here’s a handy chart on Virginia moths, butterflies, and caterpillars from The Prince William Conservation Alliance. You can also plant butterfly-friendly flowers: milkweed is particularly important for threatened monarch butterflies, and brightly-colored zinnias, echinacea, and phlox are other nectar-rich favorites.
Parasitic Wasps
Photo by Katja Shulz, via Wikimedia Commons
There is some debate whether parasitic wasps are good to have in a garden or not, so we’ll lay out the facts and let you decide for yourself whether you want to lure these fascinating critters onto your property.
Parasitic wasps - also called mini wasps, because most species in the family are tiny in size - get their names from being, well, parasitic. They paralyze their victims – many of which are notorious garden pests, including tent caterpillars, cabbage worms, aphids and hornworms – and lay their eggs on the host insect so that their larvae can feed on it (we won’t post a picture of that, but you can learn more about them here.) They will go after butterfly caterpillars as well, so you may want inspect your garden’s insect population before deciding whether you want to attract these guys.
Parasitic wasps are also pollinators (only their larvae eat insects,) and some of their favorite plants include marigolds, lavender, and cowpea.
Praying Mantises
A mantis at Oak Spring. Photo by Sarah Causey
Praying mantises are another insect that presents both drawbacks and benefits for gardeners. For one thing, they voraciously consume many garden pests, including mosquitoes, flies, grasshoppers, roaches, stinkbugs, and Japanese beetles. However, they’ll also prey on your garden’s good residents, like bees, butterflies, and spiders. It’s not uncommon for larger individuals (particularly European and Chinese mantises) to attack hummingbirds, small lizards, and frogs, as well as each other.
If you have a big pest problem in your garden, having a few mantises around is probably going to be quite a help for your plants. You’ll want to particularly keep an eye out for native Carolina mantises, which are slightly smaller and browner than the non-native species. If you want to make your garden attractive for these interesting insects, make sure you have some ground-cover plants for them to hide in – such as hostas – and a water source available.
Cicada Killer Wasps
Photo by Judy Gallagher, via Wikimedia Commons
Although these large wasps can be intimidating, they pose very little threat to humans, taking out their aggression on plant-eating cicadas. You’re likely to spot them in your garden during the summer, when the females dig tunnels in sandy areas and use their long stingers to paralyze cicadas, carrying them into the burrows for their larvae to feed on (the stinger-less males aren’t particularly helpful with either endeavor.)
Although cicada killers will buzz around you if you come to close to their nests, the females are unlikely to sting you – and the males can’t sting you. If you see any in your garden, we recommend letting these helpful wasps go about their cicada-killing business!
Lady Bugs
Lady bugs at Oak Spring. Photo by Sarah Causey
An enemy of the aphid and other small, soft-bodied pests, lady bugs are a great pest-controller for gardeners. A single lady bug can eat 50-60 aphids a day, and may eat up to 5,000 in their lifetime. Unlike non-native Asian Lady Beetles – which look very similar, apart from a white “m” marking at their heads, and also eat aphids – lady bugs don’t overwinter inside houses, and don’t bite if handled or threatened.
While you can buy lady bugs for your garden, doing so can bring unwanted parasites into your ecosystem, since many lady bugs available for purchase are captured in the wild. Since they also feed on pollen, growing a variety of herbs and blooms – including dill, chamomile, Queen Ann’s lace, and marigolds - a can attract local lady bugs to your property.
Ground Beetles
Photo by Bernard Dupont, via Flickr
Although not all members of the beetle family are good for gardens (we’re looking at you, Japanese beetles,) ground beetles can be a staunch ally in your battle against garden pests. There are over 1700 species of these beetles in the United States, most of which are fairly small and black, brown, or metallic in color. While a few species will feed on weed seeds, most are carnivorous, and will feast on pesky critters like snails, slugs, and cabbage worms. They will also eat earthworms, but are not a significant threat to your worm population. To attract them to your property, create mulch-covered areas with rocks and logs, which make great beetle hide-outs. You can also try collecting a few from a nearby wood pile to relocate to your garden.
Want to read more about beneficial bugs? Check out our blogpost from 2017 about protecting native pollinators.