XXV. 



LETHARGY IN CATERPILLARS 



One of the most inexplicable phenomena in the 

 life-history of butterflies is the fact that during 

 the only period of activity in the preparatory 

 stages, a period when all the energies seem to be 

 concentrated on eating and growing, there should 

 occasionally intervene a lethargic period when all 

 activities are suspended, the creature partakes of 

 no nourishment, moves at most only by its own 

 length to secure a position more to its liking, as 

 a drowsy sleeper turns in bed, and that this period 

 should last for weeks or even months. 



There are lethargic periods in the life of every 

 caterpillar, when it has gorged itself to the full 

 and rests quietly to digest its meal ; but these last 

 at most but a few hours. For those that feed ex- 

 clusively by day, or by night, as the case may be, 

 there is also that slightly longer diurnal period 

 when they enjoy a period of quiet shared with a 

 great body of their fellow creatures, including our- 



