Two Woolly Bears

     On October 5, 2016, the weather in Lancaster County, Pennsylvania was clear and cool, but the sunlight was warm.  It was a perfect October day.  While driving through Lancaster County farmland that afternoon, I came upon a quarter mile plus stretch of rural road where several fuzzy caterpillars were crossing it.  Every October in my lifetime, I saw an occasional black and orange woolly bear caterpillar determinedly crossing a country road, but never had I seen as many bristly caterpillars in one place at one time as on October 5.  There must have been scores of them on the road and along its edges, often in bunches of three to five.  I wondered how many more were in the three feet deep edges of mowed grasses and other vegetation just off the roadway.
     Not knowing all the answers about caterpillars, at first I thought I was seeing up to five different kinds of them, including the typical black and orange woolly bears, plus other larvae with white, pale yellow, rusty-orange or dark "hair".  Each one of those other caterpillars had only one color of hair.  But upon research, I discovered that the more mature woolly bears, which are the larvae of Isabella tiger moths, have black bristles only, not the black and orange of younger woolly bears.  And I noted that the caterpillars of Virginian tiger moths have white, yellow or orange hair.  I surmise I was only seeing two kinds of woolly bears, that of Isabella tiger moths and Virginian tiger moths, both of which abundantly inhabit the eastern United States.           
     Adult, winged Isabella tiger moths are yellow-beige with dark spots on the upper side of their stout abdomens.  Small moths, they have wing spans of up to two inches.  And they have a well-developed hearing organ on each side of the thorax.  But they don't eat as adults; only mate and lay eggs.  Their larval form consumes grass, clover, dandelions and other, common kinds of field plants close to the ground.  There are two or three broods of Isabella tiger moths a year and the last one hibernates in a safe place in the ground through the winter.   
     Adult, winged Virginian tiger moths are small and white, with long "fur" on top of the thorax and dark on the chunky abdomen.  They, too, don't eat as adults.  Each female extends an organ that emits a pheromone that males of their kind smell and follow to the females to mate.  Again, this species has two or three broods a year and the last one hibernates through winter.
     Virginian tiger moth caterpillars, like the larvae of Isabella moths, ingest grass, clover and other ground-hugging plants in fields and along rural roadsides.  The abundant food sources of both these kinds of tiger moths in the larval stage of development are why we see so many of these caterpillars in autumn.       
     I can't venture a guess as to why there were so many bristly caterpillars along that one grassy strip of country road.  Perhaps several females of both species laid eggs on the plants in it.  The life histories of many kinds of insects are complicated and difficult to understand.  But even when we don't understand all the mysteries of life, it is still fascinating beyond belief.  We can be inspired by nature even when we don't know everything about it.  And, perhaps, the better part of the beauties and intrigues of nature come from not knowing everything about them.