What are beneficial insects? Well, I can think of many of them. But I have had a lot of experience. When I think about my garden, whether it is the kitchen garden or the cottage garden, I know that there will be problems. These problems stem from insect pests, fungi, and other organisms. But if I have done my work properly in introducing and attracting beneficial insects, then I know that overall, my problems will be lessened. Even the annoying Japanese beetles have become munchies for insects in my garden.
When you think about attracting beneficial insects, the best thing to start with is increasing native plants and biodiversity. Our native beneficials prefer to get added sustenance from native plant flowers. What do they eat besides other insects and fungi? Well, pollen. And where do we get pollen? On flowers of course! The more types of flowers you have in the garden, the more insects you get. And attracting beneficial insects is a must for an organic gardener.
What Are We Attracting to the Garden?
When attracting beneficial insects to the garden, it is a good idea to know exactly what you are looking to bring in. Ladybugs or lady beetles for one, are some of the most well-known beneficial insects and yet they are just one group of beneficials. There are many more, and many are more important. To me, when combatting Japanese beetles, I like to have a wide range of assassin bugs on hand. But there are more yet. What are they and what do they eat?
Lady Beetles
Did you know that there are 481 species of lady beetles? That should surprise most of you. And some of them are not even beneficials, but pests in the garden. However, the ones we associate with most are predators of mites, aphids, and other “bugs”. Most of the adults do not feed much, but they do eat some pollen and prey. The larvae however, does eat a lot of prey. Note: It is not recommended to buy lady beetles to add to the garden. Most commercially sold beetles come from the West Coast and are not adapted to eating the pests of the rest of the country.
Lady beetles and their larvae eat aphids, spider mites, other mites, mealybugs, thrips, whiteflies, and other smaller arthropods. Common lady beetles in the Central Great Plains include the following:
- Seven spotted lady beetle
- Convergent lady beetle
- Pink spotted lady beetle
- Twice-stabbed lady beetle
- Twenty-spotted lady beetle
Mantids
Also commonly called praying mantises, mantids are one of the larger predators in the garden. There are several species in the United States, two of which are introduced from Asia and Europe. The Chinese mantid is the largest species in North America, and is naturalized throughout most of it. The Carolina mantis is the second most common species in our region. Mantids eat a variety of arthropods including butterflies, bees, wasps, beetles, and flies. You might even say that mantids are more pest than predator!
Predatory Stink Bugs
These are also called shield bugs because of the 5-sided shield-shaped body. The species which are predatory eat a variety of caterpillars, other bugs, grubs, and more. One of the most heart wrenching discoveries I had a few years ago was finding a spined soldier bug feeding on a monarch caterpillar! It was awful. But they eat other insects and caterpillars as well.
Common predatory stink bugs include:
- Spined soldier bug
- Anchor stink bug
- Damsel bug
Assassin Bugs
In the time since I started increasing biodiversity and decreasing pesticide use on our farm, the number of assassin bug species has more than tripled. I used to only see the North American Wheel bug and the jagged ambush bug, but now there are at least 14 species on our farm. Assassin bugs eat a wide range of insects, including Japanese beetles, moths, butterflies, flies, and more. Common species include the following:
- North American wheel bug
- Jagged ambush bug
- Pale green assassin bug
- Bee assassin
- Spiny assassin bug
- Orange assassin bug
Lacewings
There are a lot of lacewings in North America, making identification difficult. They are generally subcategorized into green or brown lacewings. Green lacewing adults rarely feed on anything but pollen, while ALL their larvae are predators. Brown lacewings however, are predators as both adults and larvae. They are commonly used in commercial nursery and greenhouse production as they do a better job of eating aphids and mites than lady beetles.
Other Predatory Insects
Besides the above species, there are many more predatory and parasitoid insects which you WANT in the garden to help combat the myriad of plant pests and fungi. Yes, there are insect which feed on fungi too. The following is a small list of some of the different beneficials you would want to attract.
- Owlflies
- Mantisflies
- Ground beetles
- Rove beetles
- Soldier beetles
- Tiger beetles
- Robber flies
- Soldier flies
- Long-legged Flies
- Syrphid flies
- Tachinid flies
- Wasps (all)
Attracting Beneficial Insects with Biodiversity and Native Plantings
Native plants are perhaps the most important addition to the garden as they not only increase biodiversity but also help in attracting beneficial insects. One of the easiest ways to increase natives and biodiversity is by adding a meadow or prairie garden into your landscape. Meadows do not have to be super large; mine is only 20 feet wide by 40 feet long, a mere 800 square feet. But I have also made gardens full of natives no bigger than 100 square feet.
There are certainly some species of plant which are better for attracting beneficial insects than others. Native grasses for example, do not attract many insects, except for grass skippers and pests. But the stems of big bluestem, Indiangrass, switchgrass, and prairie cordgrass do provide some overwintering sites for native bees. Many others however, provide hollow stems as nesting sites as well as flowers with pollen and nectar.
Top 20 Native Plants for Attracting Beneficial Insects to the Garden
- Mountain mint Pycnanthemum species
- Rattlesnake master Eryngium yuccafolium
- Culver’s Root Veronicastrum virginicum
- Purple coneflower Echinacea purpurea
- Cup plant Silphium perfoliatum
- Butterfly milkweed Asclepias tuberosa
- Common boneset Eupatorium perfoliatum
- Giant goldenrod Solidago gigantea
- Hairy aster Symphyotrichum pilosum
- Woolly verbena Verbena stricta
- Swamp milkweed Asclepias incarnata
- Western ironweed Vernonia baldwinii
- Common milkweed Asclepias syriaca
- Daisy fleabane Erigeron strigosus
- Bitter sneezeweed Helenium amarum
- Tall thistle Cirsium altissimum
- Greyhead coneflower Ratibida pinnata
- Aromatic aster Symphyotrichum oblongifolium
- Golden Alexanders Zizia aurea
- Hemp dogbane Apocynum cannabinum
Other Plants Which Can Help Attract Beneficial Insects
While these are not natives, they can be added to spaces in the garden for attracting beneficial insects. It is best to keep numbers of nonnatives lower to prevent the risk of invasiveness.
- Zinnia
- Mexican sunflower
- Brazilian verbena
- Calamint
- Ornamental onion
- Tall sedum
- Catmint
- Wild carrot
- Yarrow
- Garlic chives
- Dill
- Fennel
- Garlic Chives
- Chives
- Coriander
Other Ways to Attract Beneficial Insects
There are a few other things you can do when attracting beneficial insects to your garden. One thing to do is to completely (if possible) cut out all pesticides. This has made such a hug difference in my landscape. I even stopped weed killers and just started using cardboard to kill grass. Now, even in winter I find new species of insects such as beetles, moths, and flies.
Another way is to provide homes. The best way to do that is to leave some brushy piles in little used spots of the landscape. Made up of logs, brush, and leaves, you can find many insects making their homes their. Soft landings under keystone trees (oak, hickory, elm, cottonwood) can also provide a place for insects to drop from the trees or lay eggs.
Conclusion
Attracting beneficial insects to your garden can improve your plants health. Beneficial insects are responsible for keeping pest populations low enough for plant defenses such as auxins and tannins to be produced for protection. If your diversity is high enough, you should have few problems with pests such as aphids, mealybugs, mites, beetles, and other plant eating insects.
Happy planting!
