Insects That Help Your Garden

by J. Lynn Cutts, PhD
HomeOwnerNet Columnist

I’ve written before about some of the bad guys in the insect community, but fortunately, just as with us humans, the bad guys are in the minority. In fact, less than 10% of the entire insect population actually causes any damage at all. So, it’s time the good guys receive equal attention. Two of these hero’s are the lady bug and the lace wing.

Who isn’t familiar with the little red and black spotted lady bug, or hasn’t chanted “Lady bug, lady bug, fly away home”? Well, if you have aphids, (or scale, spider mites, or mealybugs) you don’t want your lady bugs to fly away! You want them to stay right there in your garden and gobble those pests up. If the lady bugs settle in and lay eggs, pretty soon you will see larvae crawling around. These “teenagers” look like tiny orange and black spotted alligators, and have the same appetite of teens the world over, except that their favorite food is insects instead of hamburgers. One lady bug larvae will eat about 400 aphids before it turns into an adult, and then that adult will eat literally thousands of them. Lady bugs have several families a year.

Often people buy a bag of lady bugs, bring them home, and release them in the evening, only to get up the next morning and find nary a trace of the little fellows because they have all flown away. What can you do to make them want to stay? First, don’t use any lingering pesticides (such as malathion or kelthane) for 3 or 4 weeks before you release the lady bugs, or any other beneficials. Switch to insecticide soaps or plain water to knock those aphids off. Second, release your lady bugs at night, while it’s cool, immediately after giving your plants a generous sprinkle of water. (this is about the only time you should water in the evening!) The combination of moisture and the cool evening temperatures will convince your lady bugs to hang around, at least overnight. By morning they will be hungry, so they will look for breakfast before they leave. If there are enough aphids, thrips, or other appetizing ( to the lady bug) insects around, they just might stay. You can provide even more encouragement to settle down by spraying a commercial preparation of insect food, such as Wheast or Honeydew, on a few lower leaves of the aphid infested plants, or plant marigolds, yarrow, or angelica, which attract lady bugs.

Another trick is to release only a few lady bugs at a time, over a period of about a week, instead of emptying the entire bag all at once. Store the rest in the refrigerator (NOT in an airtight container!), but warn all the members of your family! And be sure to handle your lady bugs gently, or they will fly away.

Lace wings are a type of fly, but they look nothing at all like that ugly black house fly. They are very delicate in appearance, less than 3/4” long, with two pairs of pale green transparent wings. Adult lace wings primarily feed on honeydew, but their larvae, also called “aphid lions”, have voracious appetites, especially for aphids, thrips, spider mites, mealy bugs, and leaf hoppers. They also eat moth and butterfly eggs, and caterpillars. Like the lady bugs, these adolescent lace wings look like spiny alligators.

When you order lace wings, order eggs, not larvae. Hungry larvae are liable to turn cannibal and eat other lace wing larvae if there is no other food source. The eggs are tiny, almost microscopic, so don’t be upset if you don’t see anything obvious. They will come in packing material which will provide them with some food if the eggs should happen to hatch. As soon as they arrive, spread them (and the packing material, since you may not be able to see the eggs) around your garden, placing them on the lower leaves of the plants which need their services. Unlike lady bugs, lace wings should be released during the day.

Lace wings are less likely to fly away than lady bugs, but you still to provide them with food. The insect population in your garden should keep the larvae happy, but you will need to provide the adults with nectar just as I recommended for the lady bugs. It’s worth keeping those adults around, too. Although they may not eat a lot of bugs themselves, they will go on and continue to lay eggs all summer, which hatch into hungry larvae in 6 to 12 days, assuring you a continuing supply of ravenous teen aged lace wings.

When using these beneficial insects, remember, pesticides don’t differentiate between the good guys and the bad. In fact, lady bugs and lace wings are extremely susceptible to these poisons. So if you wish to establish a population of beneficials in your garden, avoid chemical pesticides.