252 



JOURNAL OF ECONO^IIC ENTOMOLOGY 



[Vol. 8- 



The larva is capable of moving from place to place within the host 

 egg, locomotion being effected by the lashing of the tail and to some 

 extent by the action of the mandibles. During the early part of its 

 life the larva is very active and by the continual working of the tail 

 and mandibles the contents of the host egg are disorganized. 



The first stage larva feeds by a series of sucking motions by which 

 the food is drawn in through the mouth into the pharynx and from 

 here into the stomach, which is nothing more than a blind sac. Here 

 the food is rolled backward and forward by the movements of the 

 larva and probably by the contraction of the body muscles. 



The length of the first larval stage is about two or three days and 

 during this time the larva increases to about twice the original size, 

 most of the growth occurring in the body region. 



At the end of the first stage, the larva, which has lost its external 

 constriction and is ovate in shape, becomes inactive. Transformation 

 takes place within the old skin, the body shrinking back from the old 

 cuticula which has become thin and soon bursts near the cephalic end. 

 The larva graduallj^ moA^es out of the old skin and the moult is com- 

 plete. 



The second larval stage (Fig. 11, C) is ovate in shape and occu- 

 pies about two-fifths of the host egg. The tail-like process of the pre- 

 ceding stage has disappeared and the mandibles have become greatly 

 reduced in size. Segmentation of the body shows faintly and ten or 

 eleven segments can be distinguished. Tracheation becomes apparent 

 in this stage and four or five pairs of well developed spiracles are notice- 

 able. This stage feeds in much the same manner as the first larval 

 stage. The food is apparently sucked into the pharynx, passing 

 through the oesophagus to the stomach where digestion occurs. The 

 stomach is a blind sac and until just before pupation no excrement is 

 voided. Digestion is facilitated by the constant churning of the food 

 back and forth by the contractions of the muscles of the stomach. 

 These contractions are somewhat regular in occurrence. They may 

 start from either end of the body and move to the other end, they 

 may start simultaneously from each end of the body and move to the 

 center, or they may start at the center and run to each end. About 

 three contractions start from the anterior end to one from the posterior 

 and there are about two contractions per minute. 



In about three days the larva has reached its full development and 

 is ready to pupate. At this time all the contents of the chinch bug 

 egg have been destroyed and the larva nearly fills the shell. 



Length of Larval Stage. — It was possible to carry a number of 

 larvse through to pupation and thus the length of this period was deter- 

 mined. During August several larvse were kept under constant obser- 



