Beneficial insects

by Clare Liptak published Mar 16, 2014 10:55 PM, last modified Mar 16, 2014 11:01 PM
Not all the insects in our gardens and landscapes are out there trying to damage our plants. We can actually attract insects that are beneficial.
Beneficial insects

Ladybugs going for a walk

Not all the insects in our gardens and landscapes are out there trying to damage our plants. In fact only about 10% of the types of insects known to science are harmful to people, plants, pets or fabric.


You don’t have to buy beneficial insects such as ladybugs; many beneficial insects live in New Jersey. Ladybugs, lacewings, parasitic wasps, and my favorite, the big-eyed bugs, all feed on plant pests and they’re all common in NJ. They don’t bite people or animals; they don’t feed on fabric; and most are so small you would never notice them. So you don’t have to buy them, just make your yard hospitable to them and they, and many other “good bugs,” will stick around helping you have a beautiful landscape.


Green Lacewing
Green Lacewing
Lacewings and ladybugs eat aphids, as do hover flies which are also called syrphid or flower flies. Aphids are a common insect pest on many plants in the yard. They feed on the leaves and young shoots, sucking plant sap.


Some common and attractive garden plants will bring more of these helpful insects to your yard for the growing season. Most flowering shrub are useful because some of these insects, parasitic wasps and lacewings for example, eat only nectar and pollen as adults.



Goldenrod attracts ladybugs, green lacewings and big-eyed bugs, because they feed on its abundant pollen. That last insect is the primary predator of chinch bugs, a common lawn pest, but it also eats, aphids, leafhoppers, spider mites and insect eggs. Goldenrod takes the blame for the hay fever problems caused by ragweed. A beautiful native perennial, goldenrod is a late summer bloomer with gold or yellow flowers.


Coreopsis (also called beggar’s tick which blooms along roadsides in September), candytuft, and the common morning glory attract hover flies. The immature stage of the fly is a pale green maggot, about three-eighths of an inch long, that eats scale insects, aphids and leafhoppers.


Horn worm
Tomato hornworm
Any of the wildflowers in the daisy family will bring in tiny parasitic wasps that attack the immature or caterpillar stage of the pest insect. The wasp will lay an egg in the body of a plant pest such as a gypsy moth, or a tomato hornworm. The egg hatches inside the caterpillar and feeds on its muscles before it enters a resting stage called pupation. If you have noticed the green hornworm among your tomato plants, you’ve seen the host of the parasitic wasp. If the hornworm has white spindle shaped cocoons on the outside of it’s body, it’s dying because of the wasps. Remove the hornworm from your tomato plants, but don’t kill it. Leave it outdoors in some sheltered place so that the tiny wasps can emerge from the cocoons. That way these beneficial creatures will be more likely to stay in your yard.


And by the way, one so called beneficial insect, the praying mantis /mantid, doesn’t accomplish that much. You start with an egg mass of about 200 eggs and you think your pest worries are solved. The problem is that after the young ones hatch, they eat each other. The also eat good guys such as honeybees or the ones I’ve listed above. By the way, the Mexican Bean Beetle is in the same family as the ladybird beetles, but don’t be fooled. It’s a pest.


*Read the article, “Six ways to keep beneficial insects in your yard” for more information.


You will probably never notice adult flower flies but you might see the immature stage feeding on aphids. You probably won’t see the tiny parasitic wasps either, but you might see their offspring before they hatch from cocoons. Go to the following sites to see images of several beneficial insects:


Clare Liptak, retired Somerset County Agricultural Agent, is an IPM scout, horticulturist, and Certified Tree Expert #208.



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