Purdue Extension Service

Vanderburgh County, Indiana

Insect Pests Should be Appearing Soon

By Larry Caplan, Extension Horticulture Educator, Vanderburgh County, IN

For the Evansville Courier and Press, May 23, 2008

Late May and early June is the time period when we should be expecting to see certain troublesome insect pests. Early detection and early control can protect your yard, garden, and family from harm.

The first insect pest I'm concerned with is the mosquito. Mosquitoes lay their eggs in standing water, such as ditches, fish ponds, storm sewers, and even tires and children's toys. Anything that holds water is a potential breeding site for mosquitoes. With all the rain we've had this spring, we may have a very large mosquito population popping up very soon.

Besides the itchy bite, mosquitoes carry many diseases, such as West Nile virus, encephalitis, and heartworm in dogs and cats.

Protect yourself and your family by draining all water-holding objects, including the guttering around your roof, birdbaths, children's toys, and tires. Have your pets treated with heartworm preventatives, available from your local veterinarian. Wear repellents that contain the chemical DEET (check the label before using this on children).

Another insect that should be appearing any day now is the bagworm. Bagworms are caterpillars that live inside spindle-shaped bags which they construct to protect themselves against birds and other enemies. These bags, composed of silken threads and bits of foliage, look so much like a part of the tree that they may go unnoticed until extensive damage has occurred. Bagworms feed on many plants, but seem to prefer evergreens, such as juniper and Eastern redcedar.

Bagworms hatch out in the Evansville area around the first of June. The newly hatched bagworms are very sensitive to the insecticide B.T. (Bacillus thuringiensis, sold as Dipel). This naturally occurring bacteria only kills caterpillars, so it is very safe for humans, nesting birds, bees, and other organisms. Once the bagworms get to about an inch long, the B.T. doesn't work as well, and other insecticides will be needed.

Japanese beetles should also be appearing at any time now. These beetles are about one-half inch long, and are metallic green and bronze in color with a row of white tufts (spots) of hair on each side of their body. They feed on over 350 different species of plants, but prefer roses, grapes, fruit trees, and lindens. They will be present from early June through the end of August.

Protecting your plants from Japanese beetles is difficult for several reasons. They do not all emerge from the ground at the same time, so one treatment rarely works. If you treat your plants with insecticide, the beetle must eat some of the leaf in order to die. They also fly up to two miles in search of food, so controlling the grub stage or using beetle traps doesn't always work.

I'll provide more information on each of these insect pests over the next several weeks. If you can't wait, you can get Purdue's publications on these pests by calling the Extension Office at (812) 435-5287.