356 TEXTBOOK OF ZOOLOGY 



By carefully removing the membranous tergites of the abdomen 

 the heart can be seen to consist of a thin-walled dorsal vessel with 

 paired lateral openings into the body cavity. The blood is forced 

 forward through the heart chambers by the pulsations of the heart 

 walls. There are no arteries and veins, which means that the heart 

 serves mainly as an agitator of the body fluids, helping to distribute 

 the absorbed food to the tissues. 



The tracheal system is well developed for carrying the air from 

 the spiracles to all parts of the body. 



There are many changes in the digestive system of the June bug 

 as it passes from the larval stages to the imago. The alimentary 

 tract of the larva consists of a straight tube, except for a bend in 

 the colon. It is much greater in diameter than in the later stages 

 due to the nature of the food, which consists of roots, humus, and 

 some soil. The food passes from the mouth or buccal cavity into 

 the esophagus and then into the crop. At this point there is a valve 

 between the crop or gizzard and the mid-intestines. Two rows of 

 gastric caeca are present on the anterior end of the midintestines. 

 This is a very unique feature, as it is rarely met with in larval 

 stages of other insects. The large saclike stomach or mid-intestine 

 of the larva is transformed into an elongated coiled stomach in the 

 adult, without the two rows of gastric caeca. At the posterior end 

 of the midintestine and in front of the pyloric valve are ten pairs 

 of pyloric caeca. The hind intestine consists of the ileum, colon, 

 and rectum. There are four Malpighian tubules connected to the 

 hind intestine. In the pupal stage the gastric caeca have disap- 

 peared, and the tract is becoming much elongated and coiled. In 

 the adult the excretory organs, the Malpighian tubules, arise in the 

 ileum just posterior to the pyloric valve. They extend into the 

 body and then end blindly at the junction of the colon and rectum. 



The nervous system consists of a ventral nerve chain, a brain, or 

 supra-esophageal ganglion, a nerve ring which connects the brain 

 and the foremost or infra-esophageal ganglion. There are eight 

 ganglia in the ventral nerve chain, four in the thorax and four in 

 the abdomen. 



The life histories of the June bugs vary in length from three to 

 four years, depending upon a number of ecological factors. The 

 adult females dig into the ground and deposit from a hundred to 

 two hundred eggs. The larvae are commonly known as ''white 



