6 GUIDE TO INSECTS. 



Except in the lowest forms (the Aptera\ insects undergo meta- 

 morphoses, i.e., distinct changes as they grow to maturity. The 

 stages are : 



1. The egg. 



2. The larva. The insect as it leaves the egg ; the grub or 



caterpillar state. 



3. The pupa. The stage immediately preceding the perfect 



state ; the chrysalis state. 



4. The imago. The perfect insect. 



Insects do not grow after they get to this state. 



When the larva and pupa stages are nearly similar, and both 



Fig. 2. 



Larva, pupa and imago of a Brazilian locust, Titanacris cristata ; 

 % nat. size. (125.) 



more or less resemble the perfect insect, the word nymph is often 

 used for both. 



Table- In some instances the changes are gradual, not very distinct, and 



case 29. ^ Q difference between the larva and perfect insect is slight. When 

 ^is is the case the insect is said to undergo incomplete meta- 

 morphosis. Examples of a large Brazilian locust (Titanacris cristata, 

 1 25, fig. 2) are exhibited, also a Eurycantha (1 23), Pseudophyllanax 



