THE CANADIAN ENTOMOLOGIST. 49 



LENGTH OF LIFE IN BUTTERFLIES. 



BY SAMUEL H. SCUDJJER, CAMBRIDGE, MASS. 



Aurelians are frequently asked how long butterflies live. By this is 

 generally meant what is the length of life of the mature insect. As is 

 generally known, each species passes through one cycle of its existence 

 once a year, though it very frequently happens that two, three, or even 

 more generations succeed one another during a single season, and it has 

 been supposed (though never proven) to be the case with some that two 

 or more years are required for this cycle ; as is known to be true of some 

 other insects. But with regard to the length of life of the butterfly itself, 

 there is not a little variety : when the disappearance of a given butterfly 

 is in consequence of the approaching cold season it may well be and often 

 is the case that the butterfly has merely gone into winter quarters to ap- 

 pear again on the wing the ensuing spring. In cases like these, the 

 duration of life of a butterfly may be as long as eight or nine months or 

 even more, for there are .hibernating butterflies which emerge from the 

 chrysalis by the beginning of August or even in July, but which do not go 

 into winter quarters until September, October or even November, then 

 appear again the next season as soon as advancing spring has begun to 

 make itself felt, and continue upon the wing sometimes through June, 

 sometimes even into July. It is impossible to say certainly whether or 

 not the individuals flying latest in the spring number among them any 

 which were earliest to escape from the chrysalis in the preceding season. 

 But setting aside the chances of capture by their enemies, there is no 

 ' reason to believe it impossible, and that they may spend and probably in 

 many instances do spend fully ten months of the year in the winged con- 

 dition. 



This conclusion may be reached also in another way. We may add 

 together the ordinary life period of the egg, the time it takes the caterpil- 

 lar to reach maturity, and the period of the chrysalis, and in these hiber- 

 nating butterflies we shall rarely find that these stages together occupy on 

 the average more than two months. The remaining ten months must 

 therefore be the average time spent upon the wing. That many may live 

 eleven months or even twelve seems probable, for a butterfly may continue 

 to fly for some time after the first eggs are laid, especially in the case of 

 those which lay but one at a time, where the eggs do not develop in the 



