April, '15] 



McCOLLOCH: CHINCH BUG EGG PARASITE 



255 



place is found the actual insertion takes place. The parasite assumes 

 a rigid position, the tip of the ovipositor touching the surface of the 

 egg. The two pieces composing the sheath of the ovipositor are then 

 pushed and mthdrawn alternately for some time until a hole is made 

 in the shell. The inner valve of the ovipositor, which is chitinized 

 and sharp, is then suddently thrust into the egg. Oviposition imme- 

 diately follows this procedure and is distinguishable by a slight swell- 

 ing which starts at the base of the ovipositor and passes in a 

 wave-like motion to its tip. Immediately^ following oviposition the 

 inner valve of the ovipositor is withdrawn and at the same time the 

 caudal segments of the abdomen are extended to the surface of the 

 chinch bug egg and the ovipositor is then mthdrawn. 



The female may then walk away or she may endeavor to oviposit 

 again in the same egg. The entire process of egg deposition may 

 require from one to five minutes. The parasites do not seem able to 

 distinguish parasitized eggs from normal ones. In the course of the 

 season females were observed ovipositing in parasitized eggs, egg shells 

 from which chinch bugs or parasites had emerged and eggs from which 

 parasites were emerging. As many as three females were seen ovi- 

 poisting in the same egg at the same time. At no time was a female 

 seen attempting to parasitize eggs other than those of the chinch bug. 



Oviposition may occur at any time of the day or night. In the 

 laboratory parasites were supplied wdth eggs at all hours and egg laying 

 occurred soon after. Parasites confined in darkness were fully as 

 prolific as those kept under normal conditions. 



The period of oviposition may extend from two to eleven days, 

 the maximum deposition usually occurring the first or second day. 



Number of Eggs. — The number of eggs that a female could de- 

 posit was determined for about 300 individuals and was found to vary 

 to a great degree. This variation was due to a number of factors, 

 such as the number of chinch bug eggs supplied, the age of the eggs, 

 food, fertilization, and age of the female. 



Two hundred and twenty-six females parasitized an average of 16 

 chinch bug eggs or 53.5 per cent of the eggs supplied. The largest 

 number of eggs deposited by a single female w^as 54 and this was by an 

 unmated female. Seven females deposited over 40 eggs each and 

 twenty-one females deposited over 30 eggs each. 



Sixty females that had not been allowed to oviposit were dissected 

 and the number of eggs in the ovaries counted. The largest number 

 of eggs found was 36 and the lowest 5, while the average was 22. 



Thirty-nine females that had been supplied regularly with chinch 

 bug eggs were dissected after death and the average number of eggs 

 remaining in the ovaries was 11.4 with extremes of 0 and 28. 



