MOTHS OF THE LIMBERLOST 



and rain out of doors. Professor Thomson, of the chair 

 of Natural History of the University of Aberdeen, makes 

 this statement in his "Biology of the Seasons," page fifty- 

 four; "Another feature in the life of caterpillars is their 

 enormous appetite. Some of them seem never to stop 

 eating, and a specie of Polyphemus is said to eat eighty- 

 six thousand times its own weight in a day." I notice 

 Doctor Thomson does not say that he knows this, but 

 uses the convenient phrase, "it is said. " This is an utter 

 impossibility. The skin of no living creature will con- 

 tain eighty-six thousand times its own weight in a day. 

 I have raised enough caterpillars to know that if one 

 ate three times its own weight in a day it would have 

 performed a skin-stretching feat. Long after writing 

 this, but before the manuscript left my hands, I found 

 that the origin of this statement lies in a table compiled 

 by Trouvelot, in which he estimates that a Polyphemus 

 caterpillar ten days old weighs one half grain, or ten 

 times its original weiglit; at twenty days three grains, or 

 sixty times its first weight; and so on until at fifty-six 

 days it weighs two hundred and seven grains, or four 

 thousand one hundred and forty times its first weiglit. 

 To this he adds one half ounce of water and concludes: 

 "So the food taken by a single silkworm in fifty-six days 

 equals in weight eighty-six tliousand times the primitive 

 weight of the worm." This is a far cry from eating 

 eighty-six thousand times its own weight in a day and 



57 



