Beneficial garden insects for beginners
What makes a good bug good?
Most people instinctively agree that ladybugs are “good bugs.” But as a newbie gardener, what would you do if you found a praying mantis in your garden? Or a braconid wasp? Not too long ago, these discoveries would have me screaming and running for the bug spray! The idea that gardeners actually see them as beneficial put me squarely in the “gardening is not for me” category. Then one day it was our turn to try introducing beneficial insects to our garden.
After planting some broccoli and kale seedlings, our garden was suddenly swarming with little flies. We had just watched The Biggest Little Farm, so we had polyculture on the brain when searching for solutions. Polyculture farms and gardens grow multiple species at a time in an attempt to imitate the diversity of a natural ecosystem. Because of this diversity, the predators of pests are just as attracted to the garden as the pests themselves. Natural enemies suppress pest populations without harming the plants themselves. This in turn helps gardeners free their crops from pests without the use of chemical pesticides. This part all made sense to us.
So, even though I had no idea what the flies were, which part of our garden was attracting them, or whether or not they might harm the health of our newest additions, we decided to bring in ladybugs to hunt them. We had heard that they were good for gardens, and figured it couldn’t hurt. We purchased our ladybugs at the local garden store along with the alyssum and cilantro that a quick google search told me they liked to eat.
I’ll finish the story of how that turned out below, but first I’m going to share some information about ten of the most common beneficial garden insects. It’s the bit of research I wish I had done prior to purchasing ladybugs for our garden, and I hope it might shed some light on this topic for fellow beginners. Spoiler alert on the ladybug story: we made a few big mistakes. Also, being cute is not a qualifier of a beneficial garden insect.
10 Beneficial Garden Insects to know
Adorable ladybugs are helpful in the garden because they are voracious predators! Most feed on sap-sucking aphids, which reproduce rapidly and can destroy crops. Others feed on other pests including scale insects, mites, and ticks.
Ladybugs lay eggs in April and May in small clusters near aphid colonies. Hungry larvae can eat up to 100 aphids per day, each! Some estimate that a single ladybug will eat 5,000 aphids during its lifetime.
In addition to the insects mentioned above, ladybugs also need pollen. They are known to like the flowers from plants such as chives, cilantro, dill, marigold, and alyssum. Make sure you have enough of their favorite plants to keep them around and try to leave small aphid infestations alone, odd as that may sound!
Photo credit: “Ladybug Larvae,” James Mann. CC by 2.0.
Like our friends the ladybugs, aphids are the favorite food of lacewing larvae. Lacewings are drawn to gardens in the evenings by the scent of aphids and caterpillars, another favorite snack. They are also known to eat cabbage worms, mealybugs, and whiteflies.
Similar to ladybugs, lacewings lay their eggs near aphid colonies. Larvae feed for a month, during which time they can consume up to 600 aphids. Lacewing larvae are sometimes called aphid lions because of their powerful hooked mandibles and insatiable appetites.
Adult lacewings eat honeydew from aphids and nectar and pollen from other plants. If you’d like to attract and keep lacewings in your garden, plant yarrow, goldenrod, Queen Anne’s lace, or marguerite daisies.
Photo Credit: “Lacewing.” Martin Cooper. CC by 2.0.
Ground beetles are also carnivorous predators, hunting grubs, grasshoppers, snails and slugs. They also eat caterpillars, which is seen as a gardening plus. Honestly, it still bothers me to kill caterpillars. I get it, they love to eat leaves and fruit, but I haven’t yet gotten to the point where I prefer a beetle to a caterpillar.
Unlike ladybugs and lacewings, ground beetles are not drawn to flowers. They are mostly nocturnal, and seek dark, damp sheltered habitats like under rocks and boards. They are additionally hard to spot with their dark color and quick movement, so you’ll have to be on high alert if you hope to catch them in action.
Photo Credit: “Licinus sp. Carabidae,” Gail Hampshire. CC by 2.0.
Soldier beetles are often mistaken for wasps or even fireflies, though they don’t glow and have no way to sting or bite you. You can identify them by their yellow and tan coloring and the large black spot on each wing. Given their appearance, many of us might be tempted to rid them from our yards and gardens, but they are actually helpers.
Soldier beetle larvae hatches in the fall. Like other beneficial garden insects, their larvae are predators and will eat the eggs and damaging larvae of garden pests, like aphids. They then hibernate in the soil or among fallen leaves until spring.
When the weather warms and the beetles hatch, they are drawn to bright flowers like goldenrod, zinnia and marigold. Like bees, they are valuable pollinators that feed on nectar and pollen.
Photo Credit: “Goldenrod Soldier Beetle in flight 08-16-2015 046,” Richard Hurd. CC by 2.0.
Braconid wasps are parasitic insects. Yep, you read that right. Gardeners actually try to this attract parasitic wasp as a beneficial garden insect!
They are commonly known as a friend to the tomato plant, because they lay eggs under the skin of the tomato hornworm. As the eggs hatch, the larvae feed on the hornworm, basically eating it alive. As the wasp larvae pupate, they spin small cocoons that look like eggs all over the hornworm. The hornworm dies soon after the adult wasps emerge from their cocoons and the cycle continues.
Adult braconid wasps consume flower pollen and nectar. If you’re looking to attract them to your garden, you’ll want to incorporate flowers and herbs with small flowers such as sweet alyssum and chamomile.
I included a photo of the adult here, because everything I read about braconid wasps includes a tomato hornworm covered in egg-like cocoons. I personally couldn’t stomach another close look, and I was curious to know if the adults resembled paper wasps. Here’s an article about the wasp / hornworm relationship if you’re interested in learning more.
Photo credit: “Braconid Wasp,” Katja Schulz. CC by 2.0.
If you see a praying mantis and are convinced that it’s watching you, you could be correct. The praying mantis has incredible vision. It is known to see objects roughly 50 feet away, and it is the only known insect that can direct its gaze where it wishes.
Though pretty darn creepy to look at, they easily make this list of beneficial garden insects because of the large number of garden pests they prey upon. They eat anything they can catch and hold. Houseflies, grasshoppers, cockroaches, leafhoppers, caterpillars, mosquitoes, crickets, stink bugs, aphids, beetles, moths, locusts, crickets, and even other praying mantises are not safe around these guys.
As you can imagine, they are good to introduce if you have a serious bug infestation, but be careful as they will also prey upon any of the other beneficial insects you want to keep around. In addition to introducing plants that potential prey enjoy, you can also attract the praying mantis with tall grasses and shrubs that offer shelter.
Photo Credit: “Praying Mantis . Mantis religiosa,” Gail Hampshire. CC by 2.0.
spined soldier bug
Not to be confused with the solider beetle, this garden helper looks a lot like it’s cousin the pesty “stink bug,” but it can be distinguished by its pointed shoulders.
Another predator, the spined soldier bug it uses a sharp proboscis to attack its numerous prey. They are known to attack roughly 90 insect species including the Mexican bean beetle, gypsy moth caterpillar, and Colorado potato beetle, each of which can each cause serious crop damage.
In addition to reducing formidable garden foes, they also enjoy feasting on plant sap. However, unlike other pests, they are known to do so without harming the plant itself.
Photo Credit: “Spined Soldier Bug – Podisus maculiventris,” Christina Butler. CC by 2.0.
The damsel bug is a beneficial insect that is a generalist predator. Its many prey include aphids, leafhoppers, plant bugs, thrips, and small caterpillars. The damsel bug hunts these garden pests without causing damage to plants themselves. An adult damsel bug is less than one inch long, but both adults and nymphs can kill and eat prey larger than themselves. If they cannot find food for about two weeks, they will also eat other damsel bugs.
If you’d like to attract damsel bugs, make sure you have space to grow taller grasses where they can lay their eggs and overwinter.
Photo Credit: “Damsel Bug nymph – Nabis species, Green Ridge State Forest, Flintsone, Maryland,” Judy Gallagher. CC by 2.0.
Minute Pirate Bugs
I love a small insect. At less than 1/5 of an inch long, you may never even know these tiny bugs are hard at work in your garden unless you’re paying close attention.
Minute pirate bugs are one of the first insects to appear in the springtime, preying on small insects such as aphids, spider mites, and thrips. Each adult pirate bug is known to eat as many as 20 thrips larvae per day. In addition to a few pests, planting nectar-rich flowering plants such as marigold, spearmint, goldenrod, and fennel will attract and keep these tiny insects nearby.
Their sharp mouthparts might also pierce plants for sap, but the damage they cause is considered minimal. They can also bite humans, but, as with plants, the result is said to be a minor irritation.
Photo Credit: “Minute pirate bug eating thrips on a bean plant,” Gary Chang. CC by 2.0.
Yes, I know that spiders aren’t insects. I’m including garden spiders here because, if you can stomach them making a home near you, you’ll find that they can also be garden helpers. Like some of the insects mentioned above, they are not picky eaters and have a seemly endless appetite for insects. Not only will their eating garden pests help your plants, but catching flies, mosquitos, moths, and wasps may make the garden a more pleasant place to be for you as well.
Just remember the flip side to having hungry predators in your garden. They may catch some garden friends, bees, and butterflies in their webs in addition to garden pests.
Photo Credit: “Garden spider in front of tin shed,” Allen Sheffield. CC by 2.0.
takeaways to consider
- THINK BEYOND THE IMMEDIATE PROBLEM: If you want beneficial garden insects to stick around, they’ll need more to eat than the pest you’re trying to make disappear. Consider their overall needs for food, water, and shelter. Do they also eat flowering plants? Do you have the type of spaces and vegetation they need to lay eggs and overwinter? Plan accordingly.
- CONSIDER UNINTENDED CONSEQUENCES. You’re introducing beneficial insects to your garden because they love to feast on whichever pest is currently feasting on your garden crops. But, polyculture gardens are all about balance and diversity.Think of your garden like a food web, and try to imagine how the ecosystem might be impacted with each plant or animal you introduce. For example, a predator is introduced to control pest numbers, but if that predator has an insatiable appetite they could cause new problems by eating other beneficial insects (I’m looking at you praying mantis!).
- THINK LONG TERM: Attracting or introducing beneficial garden insects to your garden is a long term solution to your pest control problems. It’s a wonderful way to avoid chemical pesticides for the overall health of your garden, but you are not going to see immediate results. Remember to set realistic expectations and to plan your garden ecosystem accordingly. Also, keep in mind that you don’t want to completely rid your garden of pests. Some will need to remain in order to keep beneficial insects around each season.
Our ladybug lessons
Having read a bit more about beneficial garden insects than I had when we purchased our ladybugs, can you imagine what happened in our little garden? If you’re guessing that all flew away almost immediately in search of greener pastures, you’d be correct.
We made a few key mistakes from the start:
- To start with, we never identified the “pest” flies that were drawn to our plants. We never knew if they were actually harmful to our seedlings or if they were just annoying to us. You won’t know how to counter a garden pest, if you can’t identify the pest! I’ve since downloaded the Insect Identification app for help on this!
- If we wanted to attract more ladybugs to our garden, we should have thought long term and researched their needs beyond a very quick search on the way to the garden store!
- After identifying ladybugs’ preferred plants, we should have also taken the time to plant and cultivate them to grow the type of long term ecosystem they would need to stick around.
- Finally, we should have taken the time to let plants and pests draw them in rather than rushing to the store to buy our ladybug bucket. Not only would this have guaranteed that we were creating the right environment for our ladybugs, but I’ve since read that purchasing beneficial garden insects can be problematic. As it turns out, most ladybugs available for purchase are wild harvested while hibernating. Not knowing where they are coming from means that you might be unintentionally introducing parasites and disease to the other ladybugs in your area.
So, our experiment started with excitement and ended with … the same patches of dirt that we had at the start. Plus some worry that we accidentally spread parasites and disease among the ladybug community. While I’m not sure that our family will ever be able to warm up to making friends with garden spiders, we are certainly learning to take a closer look at who might be living in our yard.
Hope you were able to learn a thing or two about beneficial garden insects from our mistakes! If you have any tips, tricks, or other experiences that you’d like to share, please leave a comment below.