INSECTA. 431 



stages they live on extraneous food ; while in the third they seem to 

 require no nourishment, excepting what the changes they are undergoing 

 may produce. Their first extraneous food, or that which they eat in 

 their second stage, is commonly not what they eat in their fourth : more 

 especially in the case of those whose eggs are laid in the proper place 

 for food ; as many of the butterfly-kind, humble-bee, common fly, and 

 gnat. But of those which are fed by the parent, many I believe are 

 fed on a great variety of food, as the wasp, ant, &c. But I suspect 

 that the maggot of the common bee is either fed with honey, or what is 

 called the bee-bread, which is also the food of the fourth stage. How- 

 ever, I am apt to believe the bee-bread is the food of the maggot-bee 

 in store. 



"When in the second stage they eat much more than when in their 

 fourth or full-grown stage : and probably those that live on vegetables 

 eat more than any other known animal. Some insects eat no food after 

 being full-grown. This shows what a quantity of nourishment is 

 necessary for growth. 



Of the Caterpillar. — Although I shall keep to the terms head, thorax, 

 and abdomen, yet they do not wholly correspond in their uses to those 

 parts in the more perfect animals. The thorax in the insect is not a 

 reservoir for the organs of respiration ; but may be considered as thorax, 

 as far as that part in the more perfect animals is a fixed part for the 

 anterior extremities to take their action from : and, in this light, it may 

 be reckoned in the insect as thorax and pelvis combined; for the 

 posterior legs arise from it. Insects have no circumscribed visceral 

 cavities ; for the cavity of the abdomen, which is the only one that can 

 be called a cavity, has all its contents united to one another by means 

 of the air-cells and vessels, as if they were entangled in the air-vessels. 

 Both the caterpillar or maggot, when full-grown, are larger than when 

 in the fourth or perfect state. 



The caterpillar is a long body consisting of rings, forming many 

 points, giving origin and insertion to muscles for both the progressive 

 and lateral bending motions. 



During this state a perfect conformity subsists between all the rings ; 

 the head and tail being only distinguishable from their shape and 

 manner of termination. Most, if not all, caterpillars when young throw 

 out a thread from their mouths, which fixes them to the part on which 

 they are placed; and, if at any time they are thrown off, so as to 

 threaten a fall, this stops them. But they are often moved from the 

 fixed point, and often thrown off so as to be suspended. In such case 

 they can climb up by laying hold of the thread above, by their feet 



