328 INSECTS INJUEIOUS TO VEGETATION. 



trees, some are far more abundant than others, and therefore 

 more often fall under our observation, and come to be better 

 known. Such, for instance, are certain gregarious caterpillars 

 that swarm on the apple, cherry, and plum trees towards the 

 end of summer, stripping whole branches of their leaves, and 

 not unfrequently despoiling our rose-bushes and thorn hedges 

 also. These caterpillars are of two kinds, very different in 

 appearance, but alike in habits and destructive propensities. 

 The first of these may be called the red-humped, a name that 

 will probably bring these insects to the remembrance of those 

 persons who have ever observed them. Different broods make 

 their appearance at various times during August and Septem- 

 ber. The eggs, from which they proceed, are laid, in the 

 course of the month of July, in clusters on the under side of a 

 leaf, generally near the end of a branch. When first hatched 

 they eat only the substance of the under side of the leaf, leav- 

 ing the skin of the vippcr side and all the veins untouched; 

 but as they grow larger and stronger they devour whole leaves 

 from the point to the stalk, and go from leaf to leaf down 

 the twigs and branches. The young caterpillars are lighter 

 colored than the old ones, which are yellowish brown, paler on 

 the sides, and longitudinally striped with slender black lines ; 

 the head is red ; on the top of the fourth ring there is a bunch 

 or hump, also of a red color ; along the back are several short 

 black prickles ; and the hinder extremity tapers somewhat, and 

 is always elevated at an angle with the rest of the body, when 

 the insect is not cravv^ling. The full-grown caterpillars mea- 

 sure one inch and a quarter, or rather more, in length. They 

 rest close together on the twigs, when not eating, and some- 

 times entirely cover the small twigs and ends, of the branches. 

 The early broods come to their growth and leave the trees by 

 the middle of August, and the others between this time and 

 the latter part of September. All the caterpillars of the same 

 brood descend at one time, and disappear in the night. They 

 conceal themselves under leaves, or just beneath the surface of 

 the soil, and make their cocoons, which resemble those of the 

 unicorn Notodonta. They remain a long time in their cocoons 

 before changing to chrysalids, and are transformed to moths 



