30 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



of ganglia, one for each body segment, situated beneath the 

 alimentary canal, on the floor of the body cavity. 



All insects are developed from eggs, and in most cases 

 oviposition takes place on or near the host or food plant. Some 

 insects, however, retain the eggs within the oviducts until they 

 are developed, and accordingly bring forth living young. These 

 insects are said to be viviparous. In many of the plant lice, a 

 number of generations are produced viviparously and without 

 fertilization, after which another generation is produced in the 

 normal fashion from fertilized eggs. The external reproductive 

 organs are usually situated at the extremity of the abdomen. 



SENSES OF INSECTS. 



Insects seem not to be very sensitive to pain ; and some kinds 

 will live for hours if head or abdomen be severed from the 

 thorax. 



Sight is well developed, and the eyes are best understood 

 of all sense organs. Though larvae have only ocelli or simple 

 eyes, adults have also compound eyes, which are very large in 

 dragon-flies and some other insects, enabling them to see in 

 all directions at once. 



Hearing is a sense supposed to be possessed by insects from 

 the fact that many species sing or stridulate. The ears of grass- 

 hoppers are on each side of the basal segment of the abdomen, 

 and crickets have them on the tibiae of the fore legs. 



Taste is unquestionably a matter of fact in insect life, be- 

 cause the various species are able to discriminate between foods, 

 though perhaps attracted to their food by the sense of smell, 

 which is very highly developed. There is no organ correspond- 

 ing to a nose, but the sense of smell is supposed to be situated 

 in the antennae, and males have it developed more highly than 

 females ; by it the former are able to find the latter, and both 

 sexes find their food even by night. 



GROWTH AND METAMORPHOSES OF INSECTS. 



The most primitive order of insects (Thysanura) have no 

 transformations or metamorphoses, but the young, except in 

 size, resemble the adults. Most kinds of insects, however, pass 



