Here they are!
The 1996 Oxford, Ohio Woolly Bears!
And the 1997-98 El Niño Woolly Bears!

OK, I went out on my farm and captured 11 Banded Woolly Bears (Pyrrharctia or Isia isabella). I weighedthem and measured their fuzzy bodies, paying no attention to larval instar. The fuzz created some error in measurement, as does their tendency to take off or curl up while being measured. I was patient, waited for each one to settle down, and measured them quiet and uncurled. I used a caliper which could measure tenths of a millimeter accurately and measured tip to tip of fuzz at each end. If you try to measure just the body, you have to get inside their hair boundary, so they get pissed off and curl up.

Woolly Bear Uncertainty Principle: you can know the rest mass of a critter, but in motion (or at rest), nothing is certain.

Furthermore, I did not check out the developmental stage of the critters, I just caught and measured them, making sure I had eleven different individuals (not one or two at different development stages). I clocked one (Speed Racer), weighing in at an awesome 0.87 gram with a brown band of 19.9 millimeters) moving at a blazing 19.2 centimeters per second. According to my unreliable arithmetic, that is 0.045 miles per hour. This world-class event took place on December 28, 1996 when the temperature was 67 degrees Farenheit.

I did this little project because I could never find anyone to tell me how wide a "narrow band" is on a woolly bear. Brown bands were 14.2 mm to 26.7 mm long. Band width is proportional to the size of the animal. Because of fuzziness and wiggliness and curliness, weight is the most reliable? parameter to measure. On average, the Oxford animals have a brown band which is half as long as the body length.

Thus the answer to the burning question about band width! Animals are narrow banded if their bands are less than half the body length, and wide banded if the bands are more than half the length of the body.

How these animals predict anything is beyond me, but they are extraordinary creatures. Read up about them on the Web and in your library: they have the ability to tolerate very cold temperatures (they have a chemistry which acts as an antifreeze) and live a long time (for creepy crawlies). I noticed that this species overwinters as a larva (moth is the adult) and are active on sunny winter days. The dark colors and may be camouflage against predators and the fuzzy dark surface absorbs solar radiation on those chilly days.

Here are the 1996 Woolies!

Animal/weight (g) length (mm) width (mm) black head (mm) brown band (mm) black butt (mm)
One (dead) 0.56 26.4 12.8 8.6 12.1 8.4
Speed Racer 0.87 41.3 15.8 15.2 19.9 10.1
Three 1.28 44.2 17.9 15.1 22.1 10.3
Four 0.63 34.2 14.7 11.8 17.2 8.9
Five 1.06 45.9 15.5 13.4 24.7 10.9
Six* 1.26 44.6 16.1 12.9 25.7 9.5
Tiny 0.55 37.7 12.6 15.2 14.2 9.8
Eight*1.05 42.5 15.6 12.7 24.8 9.8
Nine (dead)0.77 33.6 13.3 10.8 14.7 9.9
Ten 1.11 52.7 14.9 13.3 29.3 10.1
Eleven 0.94 39.7 14.8 14.7 20.7 7.8

This image for the 1996 critters is shown at 75%, click on it to see it at full size.

The 1997 woollies at my farm have several brown bands or none. They are really different from those of the previous year. Hmmmm...

Animal/weight (g) length (mm) width (mm) black head (mm) brown band (mm) black butt (mm)
One 0.45 30.1 15.8 13.8 10.4 5.9
Two 0.45 41.3 9.9 15.2 19.9 10.1
Three 0.46 38.8 16.8 none:black band
8 mm 6 mm
from head
24.8 none
Notice the forecast statement in the news release below. For us in Oxford, the winter has been a non event. For those on the East and West Coast at the ends of the "El Niño pipeline" of atmosperic water transport, Yikes!

The Cincinnati weather data link for 1996 is for those who wish to try for some sort of correlation between weather and whether or not the woollies prognosticate...

Kansas State Research and Extension News
Released: September 19, 1997
Woolly Caterpillars No Prognosticators
MANHATTAN--Many Kansans think they'll soon be hauling out the ol' overcoat. In recent weeks they've seen very woolly-looking caterpillars. And, folklore holds that the sooner and woollier those caterpillars appear, the more severe the winter.

Winter 1997-98 may very well be severe.

But the caterpillars known as "woollybears" are no forecasters. In fact, their numbers relate to summer's weather, not winter's. And their woolliness simply reflects their particular species or how old they are, when first seen, said Leroy Brooks, entomologist with K-State Research and Extension.

"I don't know how people decided woollybears and winter are somehow tied to each other. Perhaps it's because after a summer of seeing sort of naked-looking corn earworms and fall armyworms, they suddenly find these caterpillars that look like they have on a fur coat," Brooks said. Woollybears can be pure white, brilliant rust-bronze or jet black, he added. But the kind Kansans tend to view as"seers" are banded--brown in the middle and black on each end.

All eventually become moths of the family Arctiidae, better known as tiger moths. One of the common tiger moths is medium-sized and pure white, except for small black spots on its wings. Another, generally known as the virgin tiger moth, has beautifully marked red and black front wings.

"We have them every year. Typically, their larvae or caterpillars feed on weeds and grass. In some years, woollybears can become a problem in sunflower and soybean crops," the entomologist said. "How many we have often depends on summer weather--on the windy fronts that blow through when the adults are flying up from the south, to lay eggs.

"Most Kansans don't see the resulting caterpillars, however, until the woollybears are almost through feeding. The larvae start roaming around in September and October, looking for more food and for the right spot to overwinter in the ground. They may seem to get more numerous after a cold front, but they'd act the same if the weather were

Every year in every type of weather the larvae also have the same amount of "hair," Brooks said

"How much that is depends on how old the larvae are. Woollybears go through four to five developmental stages,"
he explained. "Initially in the field, for example, they're fairly small and hairy and often go unobserved. People most often notice them when the caterpillars get about half grown, are about an inch long and seem even hairier. Just before these larvae go underground, however, they're about 2 inches long and almost furry."

"For those few people who happen to see a woollybear in its final instar, the difference in size and woolliness
probably makes a pretty big impression," Brooks said.

While on the move, the larvae may crawl almost anywhere, sometimes crossing streets or climbing fences in their search for good winter shelter.

"Last year in an unusual instance in southeast Kansas, an entire colony of woollybears invaded a shop building.
They found a nice pile of stacked lumber on the workbench and worked their way between the board by carving
galleries in the wood. They used their silk to seal themselves in so tightly that the owner had to use a wrecking bar to pry the boards apart," Brooks said.

K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has offices and research centers in 105 Kansas counties and its headquarters on the K-State campus, Manhattan.

Kathleen W. Ward, Extension Communications Specialist


Horticulture and Home Pest News at

The Yellow Woollybear Diacrisia virginica (Fabricius), Arctiidae, LEPIDOPTERA, whose caterpillar has a different striping pattern from P. isabella, has its life history and habits discussed at

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