Woolly bears invade Highland Lakes
Salt marsh caterpillars, often called 'wooly bears,' are crawling across the Highland Lakes in great numbers this spring. Staff photo by Jennifer Greenwell
Millions of furry caterpillars are currently marching and munching on vegetation across Burnet and Llano counties. These “woolly bears” are mostly harmless, but they can put a dent in the lush, green growth that has sprouted up in the Highland Lakes this spring.
While “woolly bear” is a widely used moniker for any caterpillar covered in fur-like hairs, many of the caterpillars currently on the move in the area are specifically salt marsh caterpillars, a species that comes in a variety of colors and is extremely common across the United States.
The hairs, or setae, of the salt marsh caterpillar can cause some irritation to those with especially sensitive skin, but it isn’t among the stinging, poisonous caterpillar species found in Texas.
Salt marsh caterpillars are “generalists,” according to Texas A&M University entomologist Wizzie Brown, meaning they feed on a variety of broad-leafed plants and are seen as a potential pest for farmers and gardeners as they can strip the leaves from young plants in the spring.
The caterpillars could be a problem if they congregate in your garden in large numbers, and they should be removed if you don’t want your more delicate plants damaged. They are otherwise harmless.
Insecticides containing Bacillus thuringiensis, like Bonide Thuricide or DiPel Pro, are a good, non-toxic method for controlling caterpillar populations in your yard. You can also remove the woolly bears by hand.
While woolly bears can be pesky in the garden, they are an important food source for birds and other critters that are higher up the food chain. Also, the moths they become are prolific pollinators, which benefit flowering plants.
The salt marsh caterpillar is the larva of the salt marsh moth, also known as the acrea moth. The abundance of caterpillars this spring is the result of these moths all emerging from their cocoons at once after hibernating throughout the winter.
Females lay clusters of 400 to 1,000 eggs on a host plant that acts as a nursery and immediate food source once the caterpillars hatch in four to five days.
The newly hatched caterpillars aren’t woolly when born but grow out their hair as they get older. It might take 20-45 days for the caterpillars to fatten up, depending on food availability.
When caterpillars are concentrated in the same location, like what is happening now in the Highland Lakes, they travel to find untouched food sources. That means caterpillars on the move and out in the open.
Once the caterpillars have eaten enough, they enter their pupal stage and wrap themselves in a cocoon, in which they grow into a full-fledged moth within 12-14 days.
This life cycle will continue throughout the year until no food is left or it gets chilly enough for the woolly bears to hibernate.