Caterpillars are controlled with a common insecticide

Q: I have been overwhelmed with an enormous number of caterpillars that are feeding exclusively on my passion flower vines. They are 5 to 6 centimeters in length with a pumpkin-orange body and greenish-black longitudinal stripes. They are covered with stiff black spines that are perpendicular to the body and run the full length of the body. The antennae are almost indistinguishable from the spines.

They are devastating my passion flower vines. What are these caterpillars? Are they harmful and/or poisonous? Will this insect destroy my passion flower vines? What can be done to eliminate them?

I would appreciate any information you can provide me.

- James L. Norman

A: Your caterpillars could be one of many caterpillars. There are 11,000 species of caterpillars that call the United States home. However, there are fewer native to Georgia, so identification is not impossible. I would need to see the offending critter to identify it. You could e-mail an image, and I could identify them.

In any event, all caterpillars can be controlled with liquid Sevin, a commonly available insecticide. The creatures will defoliate your vine and disfigure it horribly, but they will not kill it. A great Web site for caterpillar ID is hosted by the USDA at www.npwrc.usgs.


families.htm, or enter eastern caterpillars in any search engine.

Q: Do I need to cut back knockout roses? If so, when and how much? Anything else I need to do for it before it gets cold?

- Alice

A: Roses respond to pruning and removal of old flowers by producing more spectacular flowers in greater quantities. Regularly removing old flower heads, or dead-heading, is the key to great roses. Cane pruning is done in early spring before growth begins, while dead-heading is done throughout the growing season. You could cut back your roses now if they need it, but I would prefer to see you do your pruning throughout the growing season. During the growing season, check your plants every week and twist off the old buds. Every four weeks, cut long stems back by half. This two-step process keeps new growth coming and removes the hormone-filled hips that tell the rose to bloom more slowly.

Q: I have a baby Acoma crape myrtle tree growing next to a three year-old crape in my landscape. It's been there for a bit over a year. I wanted to leave it for a while to let it get stronger, but now I think it is time to dig it up to give it to a friend. Any suggestions on things I should do to make sure it lives? Are crapes hardy trees for transplanting?

- Diana Hofsommer

A: Crape myrtles are rough and easy to transplant. Wait until the leaves fall off this winter to transplant it. That will reduce stress on the plant because it will not be active. Dig a root ball with a diameter 10 times that of the stem at 6 inches off the ground. If the tree trunk is one inch at six inches off the ground, then the root ball should measure 10 inches in diameter. In any case, crapes are nearly indestructible.

The only thing that really kills them in Gwinnett is extreme cold. Mulch the plant well after planting to protect the roots from freezing temperatures. Water at planting and whenever the soil gets really dry to prevent winter desiccation.

Q: After many years, I finally have a backyard large enough for a garden; unfortunately, now I have to deal with a septic field.

Can you direct me to information regarding what fruits/vegetables are safe for planting in and around a residential septic field? Thanks for your help.

- Kyle Kimmel

A: Growing vegetables over a septic field should be avoided if possible, although it can be done. Basically, any fruit-bearing veggies are OK (squash, tomatoes, okra), but all root crops (beets, carrots) and low-growing leafy plants (collards, lettuce) would be suspect. If the septic field were functioning properly, then there wouldn't be any worries.

Unfortunately, there is no way to know if bacteria is leaching. You would want to be sure to wash all of the soil off any vegetables harvested. Ideally, you wouldn't have a vegetable garden directly over a drain field. The roots can clog septic lines. Stephen D. Pettis is an agriculture and natural resources agent with the Gwinnett County Extension Service. He can be reached at 678-377-4010 or Steve.Pettis@gwinnettcounty.com.