Those pesky pests: Garden questions answered

Insect pests came up in recent conversations at the Extension Office. Here are a few of the questions asked.

Q. There is a creature in a cocoon that looks like it is made of little sticks migrating across the road. My neighbor’s tree has lots of the creatures on it, and now the tree is one-third brown. What is this pest? Is there any organic solution? M.S., Lynchburg
A.  Your creatures are bagworms. They take twigs and leaves from their host plant and mix them with silk from their bodies to make a protective covering or bag. Their feeding season runs for another month, and your neighbor’s tree could be dead by then. Picking them off the tree by hand is the only control method likely to work this late in the summer. Insecticides are more effective on bagworms in June, and the organic spray sold as Dipel and Thuricide does a good job at that time. 

Q.  I recently discovered one of those large round hornet nests up in a tree, probably 20 feet up, between myself and the neighbor’s house. And I was just curious about what you felt is the proper way to deal with that? Whether I need to get it down or hire an exterminator or do it myself. Or can I just wait for cold weather to take care of it? D.M., Lynchburg
A.  Hornets are good to have around, provided their nests are not in areas of human activity. They catch caterpillars and other insects, chew them up and feed them to their young. The nest in your yard is unlikely to cause any problems because it is so high up in the air. If you decide to control the hornets instead of co-existing with them, consider contacting an exterminator. The do-it-yourself approach, on a ladder at night with an aerosol can of wasp and hornet spray, seems too risky.

Q.  I have hundreds of little black flying insects that are eating up my tomatoes and cucumbers. I have tried everything that Lowe’s has to offer, even to the extent that some of my plants are dying from the spray and powder that I have put on them. But the little bugs are still flying around, and they are so bad I can’t use my patio. Please call at your earliest convenience. R.S., Lynchburg
A.  Samples of your flying insects were sent to the insect identification lab at Virginia Tech, and they were found to be tiphiid wasps. These insects do not harm people or plants, and they were swarming in your yard for the purpose of mating. Female tiphiid wasps hunt through the soil for beetle grubs and lay eggs on them. Their larvae feed like parasites inside the bodies of the grubs, and they help to control pests like Japanese beetles. You can expect the swarms of wasps to go away in a week or two.