THE INSECT WORLD. 



differ by the lack of wings and tlie usually small size compared 

 with the normal sexless form. Pairing takes place almost imme- 

 diately, because the female is sexually mature when born, and 

 shortly afterwards eggs are laid. In many instances the egg 

 supply is exceedingly small, indeed there may be one only ma- 

 tured by a female. Even this may remain within the body of the 

 parent, who simply dries up, the skin shrivelling around and 

 forming a protection to the ovum. More usually several eggs 

 are produced, and these of large size in proportion to the size of 

 the insect that lays them. They are green or greenish-brown 



Fig. 93. 



Hop-louse, male ; return migrant. 



in color when laid, sometimes yellowish, and frequently darken 

 to black. They are placed in sheltered situations on plants, and, 

 in the case of orchard trees, are usually found at the tips of twigs, 

 around the buds, or on the leaf-scales, where vegetation will first 

 start in the spring following. They are very firm in texture and 

 very resistant to insecticides ; in fact, it is impossible to destroy 

 them except by the most caustic mixtures. It has been already 

 indicated that there are many exceptions to this general life his- 

 tory, and one kind of exception we find where species feed dur- 



