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Woolly Bear Caterpillar

COMMON NAME: giant woolly bear (larva), giant or great leopard moth (adult)

SCIENTIFIC NAME:  Hypercompe scribonia (Lepidoptera: Erebidae: Arctiinae)
HABIT:  The giant leopard moth is our largest eastern tiger moth. Giant leopard moths are nocturnal. Males are commonly attracted to lights at night. Sometimes dozens of males come to bright lights set out in good habitat. Females are less common around lights. The caterpillars larvae lack stinging spines and do not bite. However, the stiff setae are effective defenses against predators. When threatened, giant woolly bears curl up tightly to protect their vulnerable undersides. When picked up, their stiff, smooth spines are bent backward and they tend to push the caterpillars forward and out of the grip. Because of this, it is hard to forcibly uncurl them when they are in the defensive posture. Also, in this defensive posture, their bright red inter-segmental areas are highly visible as a display to warn potential predators that they are unpalatable. They are primarily nocturnal, but are often seen crossing roads during the fall while seeking sites to spend the winter or found under leaves or in wood piles by people doing yard work during spring and fall. They sometimes climb trees.

Adult moth of the woolly bear.

RANGE:  The giant leopard moth is found from southern Ontario south to Florida and west to Minnesota and Texas 
EGGS:  The nearly spherical eggs are 0.8 mm in diameter and pearly gray in color 

LARVAE: The head, thorax, and abdominal segments 4, 5, 9, and 10 of early instars are orange. Abdominal segments 1-3 and 6-8 are dark brown, and there are orange mid-dorsal and lateral lines that run the length of the body. The spiracles are yellow. The body is covered with stiff black setae. Full-grown giant woolly bears are approximately about 3 inches in length. They are black with red spiracles and inter-segmental areas and are covered with shiny black, bristly setae. Although giant leopard moth adults and caterpillars are probably well-defended against most predators, the caterpillars are frequently parasitized, particularly by tachinid flies.

COCOONS AND PUPAE: Pupae are black with reddish brown spiracles. Pupae are enclosed in thin, yellow, net-like cocoons with small amber beads at the junctions of the threads.
ADULTS: The wing span is approx. 2.25-3.6 in.  Adults are white with hollow black (or sometimes iridescent blue) spots on the thorax and black spots on the front wings that may be hollow or solid. Spots on the leading edge tend to be solid. The spots are highly variable, and in some specimens they are solid instead of hollow. Rarely, the spots are missing entirely. 

LIFE CYCLE:  There is a single brood in the North and two or more broods in the South. Nearly full-grown larvae overwinter and complete their development in the spring. 
HOST PLANTS: The giant woolly bear feeds on a variety of low-growing forbs and woody plants. This “food-mixing” results in the likelihood of eating plants that contain toxic chemicals that the caterpillars may sequester for their own defense.
CONTROL: The giant leopard moth is not economically important and control measures are neither recommended nor required.
SPECIAL NOTE: Legend has it that the larva of this moth can help predict the weather. The myth is that the reddish bands on the woolly bear can actually help you determine how severe the weather will be. The wider the bands, the more severe the upcoming winter will be. This beautiful moth is not economically important and control measures are not recommended or required.


Woolly Bear Caterpillar: A Winter Weather Predictor or Not?

Source: US Weather Service

The Isabella Woolly Bear (Pyrrharctia isabella) Caterpillar is another of the giant tiger moths found across the United States, Canada, and Mexico. 
Most people in the Midwest or New England have heard at one time or another that if you want a forecast for the upcoming winter that you should just look for a woolly bear (black at both ends and a reddish brown or rust colored in the middle) or fuzzy bear caterpillar. This same caterpillar is called the woolly worm in southern United States.  Yet another name for this caterpillar is the Hedgehog Caterpillar, because it curls into a tight bristly ball and “plays dead” when picked up or disturbed.  Whatever name they go by, they are often found in the autumn after they have left their food plants (variety of grasses and weeds including plantain, dandelion, and nettles) in search of a dark and sheltered spot where they can hibernate as larvae for the winter.

  Photo by JR Masters


  Yellow Woolly Bear caterpillars, Barton Springs in Austin, TX. Photos by Mike Mirabal





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