Louisiana has its share of caterpillar. While the end result, a moth or butterfly, might be beautiful, the larvae can range from bizarre looking to toxic. Knowing which caterpillars are benign and which are not is a useful trick for Louisiana gardeners. The presence of caterpillars can be a blessing or a curse.
Buck Moth (Hemileuca Maia)
The buck moth (Hemileuca maia) caterpillar eats the foliage of trees, especially oak. These caterpillars reach about 3-inches long and are covered in black spines. They develop into black and white moths with rusty red abdomens. In Louisiana, its eggs start to hatch from mid to late February and continue through March. If you touch buck moth spines, you'll receive a painful sting. In extreme cases, this can cause an allergic reaction that may require medical care.
Red-headed Azalea (Datana Major)
The Red Headed Azalea (Datana major) caterpillar is relatively benign, although it is definitely damaging. This fuzzy caterpillar hatches in late summer and can strip an azalea plant. This doesn't usually kill the azalea, but the eating certainly cramps its growth. The caterpillars have red heads and skins but don't bite or sting. When you see these bugs, you can remove the affected branches or leaves or, if the infestation is severe, use a pesticide.
Forest Tent (Malacosoma Disstria)
The forest tent (Malacosoma disstria) caterpillar is a moth larva that hatches in March. This caterpillar is fuzzy and blue with small, silver dots on its back. It goes for trees such as sweet gum, cherry and willow. These caterpillars don't bite and their attack looks ugly, but the eating doesn't usually harm the tree. The Louisiana State University AgCenter reports that you don't usually need to control these caterpillars but, if infestation is severe, you can spray.
Black Swallowtail (Papilio Polyxenes Asterius)
The black swallowtail (Papilio polyxenes asterius) is a striking butterfly with almost completely black wings. Its caterpillar is sometimes called parsleyworm, which gives some indication of its preferred food source -- plants in the parsley family. It also eats plants in the citrus family. Newly-hatched caterpillars start of black with a white saddle, but slowly turn lime green with black markings. If you want the swallowtail in your garden, plant dill and parsley.