286 GLOSSARY 



of wings commences in the early period of larva. After last larval 

 skin is assumed, previous to change to pupa, rudiments of wings 

 beign to form, of the size of pins' heads, beneath external covering 

 of hinder parts of thorax. They continue to grow, and just before 

 this last larval skin is cast, their existence is distinctly indicated by 

 the swollen appearance of the segments. Are much enlarged when 

 insect turns to pupa, and when subsequently pupa skin is burst, the 

 soft thick organs dry, and acquire full expansion. Their gradual 

 formation can be well seen in insects with an incomplete 

 metamorphosis. 



Workers. Females of certain social insects, such as the ant and bee, 

 the sexual organs of which are imperfectly developed. Their 

 function is to perform all the laborious offices for the community. 

 Formerly they were believed to be devoid of sex, and were thus 

 termed neuters. Experiments have proved that the cause of 

 this differentiation of sex depends upon the nature of the food with 

 which during the larval state the bee is fed. In all probability, 

 this explanation applies also to ants. 



