16 CATERPILLARS AND THEIR MOTHS 



hundred and five days. Generally the specimens which 

 pass through their stages with normal rapidity are 

 more vigorous than the slower ones. 



One or two writers have claimed that the sex of a 

 caterpillar can be regulated by the amount of food 

 given it, abundance producing females and semi-star- 

 vation males. We have made extensive experiments 

 with several species of caterpillars, and the result has 

 always been that the scantly fed produced as many 

 females, in proportion, as the full fed. The sex of the 

 caterpillar is fixed when the caterpillar is hatched, but 

 cannot be determined without dissection. Being im- 

 mature, the caterpillar cannot reproduce its kind. Its 

 organs of reproduction are not developed. 



The " whole duty " of a caterpillar is to eat and live 

 to grow up, and some caterpillars have to eat enough 

 to sustain life not only in the larva and pupa stages, 

 but in the imago stage as well, for many moths have 

 no means of taking food. Their mouth-parts are not 

 complete or developed. 



The caterpillar contains the buds which will develop 

 into the organs of the moth or imago. Even the wings 

 are present as little folds or pockets in the skin, and it 

 is in the pupa stage chiefly that these imaginal buds 

 grow into the organs which will be of use to the moth, 

 while the props and various organs which were of use 

 to the caterpillar but would be useless to the moth 

 are destroyed. 



