Q: I have a furry caterpillar on my oaks; it has a split tail and white balls on its back. What it is?
A: The larvae you described are called the White marked Tussock Moth , Hemerocampa leucostigma . This moth is widely distributed throughout eastern North America, as far west as Texas and Colorado in the United States. The larvae are known to feed on foliage of a wide variety of trees, both conifers and hardwoods. Hardwood hosts include basswood, maple, sycamore, apple, oak, poplar, willow, and elm. They are seldom a problem in forest areas but are known to attack Douglas Firs. Eggs are laid in small, white masses and hatch in the early spring, usually April. Larvae become fully grown in five to six weeks; mature larvae have been found in early May. Young larvae chew small holes in leaves and feed until they pupate in May or June. Older larvae feed on leaf edges, consuming entire leaves except for larger veins and midribs and live about 2 to 4 weeks. This chewing can cause considerable damage to shade and ornamental trees although trees are seldom killed. In the South there may be as many as three generations per year. The best control is natural parasites, predators, microbial diseases, starvation, and unfavorable weather. In urban and recreation areas, insecticides may be desirable to avoid defoliation but need only be used if a true problem exists. Finding a few of the larvae does not constitute an epidemic so no chemical control should be necessary.