LIFE HISTORY OF THE COMMON SQUASH BUG. 



23 



antennae are subequal in length. The first and second joints are sub- 

 cylindrical; the first widest, the third and fourth fusiform, the third a 

 little wider than the first, and the fourth widest. The antennae as well 

 as the legs are quite hairy. The dorsal tubercles of the abdomen and 

 the marking of the abdomen are indicated in the illustration. 



The length of the body when the nymph is first hatched is a trifle 

 less than 2.5 nm, 7 which becomes just prior to the first molt about 3 mm or 

 the same length as the next stage immediately after the molt. 



Just before each molt the nymph becomes stouter, the abdomen very 

 much rounded as if swollen, aud the color lighter. 



Second stage (fig. 4, b). — After the first molt the abdomen becomes a 

 light pruinose gray and the tubercles and all markings become more 

 pronouuced and conspicuous ; the head loses somewhat its triangu- 

 lar appearance, the eyes show more prominently at the sides, and the 

 third joint of the antennae is 

 noticeably largest. The tho- 

 racic portion is now compar- 

 atively smaller and lighter 

 in color. Immediately before 

 molting the abdomen be- 

 comes very much enlarged, 

 as though swollen, the color 

 turns nearly uniform lighter 

 pruinose gray, looking almost 

 white, and the sutures of the 

 upper surface of the head are 

 nearly invisible. Length Fig4 



-Anasa tristis nymphs : 



when first molted, a little 



stage; c, third stage; d, fourth stage 

 ahout twice natural size (original). 



newly hatched ; b, second 

 fifth stage — all 



more than 3"" u . 



Third stage (fig. 4, c). — After the second molt the larva has changed 

 but slightly except in size and in the darker color of the body. The legs 

 and antennae have increased in length, maintaining the same relation 

 to the body as at the first day of the preceding stages ; in other words, 

 the third larval stage is a nearly exact counterpart on the day of molt- 

 ing of the second larval stage on the same day in its development. 

 Immediately before molting, however, it undergoes considerable change, 

 presenting the appearance shown in the illustration. Length, about 4 mm . 



Fourth stage (fig. 4, d). — In the stages previously described the scale- 

 like process which represents the wing-pad of the fifth or last nymph 

 stage increases slightly with each molt. With the molt which ushers 

 in this stage this process shows considerable growth, approaching 

 closely to the true wing-pad of the next stage. The next most 

 observable difference between this stage immediately after molting, 

 and the previous stage at the same period of growth, is in the increased 

 width of the thoracic and abdominal portions and the general darker 

 color of the body ; the body is nearly pyriform in shape. Length when 

 first molted, 6 or 7 mm . 



