Caterpillars That Defoliates Ornamental Plants

During late summer, caterpillars cause problems for gardeners all over our state. As you know, caterpillars are the larval stage of butterflies and moths. While many of the winged adults are attractive, the damage caused by the larvae certainly is not. Because caterpillars are ravenous feeders they can cause considerable damage in a short time. Early detection and prompt counter measurers are very important.

Azalea caterpillar – This Caterpillar defoliates azaleas. Young larvae skeletonize the leaves, and the larger ones eat the entire leaf. The 2-inch long mature larva can be recognized by the red head, the read last segment, and the broken yellow (occasionally white) lengthwise stripes. When it is disturbed, the caterpillar raises its front and rear ends into the air.

Bagworm – These are general feeders that spin socks or bags of small pieces of twigs and leaf material (usually cedar). These socks are one-quarter inch to 1.5 inches in length and usually are found on foliage. The bag is carried by the insect wherever it goes. The larva protrudes the front end of its body from the bag when feeding or moving.

Sod webworms and Fall armyworms seriously damage lawns. And it’s not unusual for both to attack at the same time. Webworms are the smaller of the two species, reaching a length of only about three-quarters of an inch, compared to the one-and-a half inches for armyworms. In general, both are greenish in the young stage and then brown as they mature. Their feeding is similar resulting in notched or ragged leaf edges. However, webworms usually feed in patches while armyworms causes more scattered damages.

The orange dog caterpillar is a common pest on citrus trees. It’s eggs, whish larva like yellow beads, are laid on the newest plant growth. At maturity, the orange dog becomes a swallow tail butterfly.

If you’ve ever suddenly felt a sharp, stinging sensation while pruning a plant, you may have come in contact with an IO (Eye-oh) moth caterpillar. This caterpillar is pale green, with two stripes, one white and one maroon down both sides of its body. It has many clumps of stiff poisonous hairs. Touching these is painful to most people. In some cases, the reaction is bad enough to require hospitalization. The IO moth caterpillar, which is only one of several stinging varieties, is found on such plants as hibiscus, poinsettias, palms and many other varieties.

Caterpillars can be controlled mechanically, or with chemical sprays.

If the caterpillars are large, and few in number, they can be removed from plants by hand or if egg masses are recognized these can be destroyed before they hatch. Chemical control materials include Sevin, Malathion, and Bacillus Thuringiensis.

Seven is a stomach poison, that’s good to use on small caterpillars that are hard to find. However, Sevin isn’t a very good contact poison. So it can’t be used against caterpillars that are already quite large.

Malathion is a good contact poison, but a poor stomach poison. It’s best for use on large caterpillars. Malathion must be applied thoroughly to insure contact with all the caterpillars.

Bacillus Thuringiensis isn’t a chemical. It’s a bacterial concentrate that is deadly only to caterpillars. It won’t harm any other insects. When applying pesticides, you should always use caution and common sense. Avoid contact with the concentrate, and stay out of the spray drift. Read the product label carefully, and follow all directions exactly.

For more information please contact the Gulf County Extension Service at 639-3200 or 229-2909 or visit our website at http://gulf.ifas.ufl.edu/