18 BULLETIN 842, U. S. DEPARTMENT OF AGRICULTURE. 



the intestine is almost colorless, transparent, and void of a large 

 part of its granular food material. 



The reproductive system, composed of two branches, opens at the 

 vulva, which is situated about one-eighth to one twenty-seventh of. 

 the body length forward from the tail end. The fertile branch 

 which extends in front of the vulva is at first glandular and saclike 

 for a short distance. It then becomes smaller and continues as a 

 fine tube of uniform diameter to near the middle of the organism. 

 This tubelike portion, the uterus, is usually filled with many fertil- 

 ized eggs in various stages of development, and in old females may 

 contain hatched larvae. The uterus expands into a vesicular-shaped 

 portion, presumably the receptaculum seminis, where fertilization 

 takes place, and the latter opens into the large end of the ovary, 

 which contains mature ova. Usually the ovary folds twice, once near 

 the anterior end of the intestine and again just forward of the mid- 

 dle of the animal, and terminates in a small blind end filled with 

 rudimentary eggs. Back of the vulva there is a short, bag-shaped, 

 glandular, sterile branch of the genital organs, the function of which 

 is not understood. 



As females mature they become tightly coiled and motionless, 

 except for a slight motion of the head. Although still capable of 

 being bent, they will, if straightened out and released, quickly recoil 

 into a shape somewhat similar to that of a watch spring. 



Egg laying begins soon after the galls are formed and continues 

 for several weeks, during which time a single female may lay more 

 than 2,000 eggs. As an average of about six or seven females are 

 developed in each flower gall, the latter usually contains about 15,000 

 eggs or an equal number of larvse into which the eggs soon develop. 

 By actual count the writer has found 11,573 and 18,051 larvse in 

 what were selected as two medium-sized galls, while Dr. N. A. Cobb 

 informs him that he has found as many as 90,000 in a very large gall. 

 Like larvse of the first stage, adult females as well as males are 

 incapable of withstanding unfavorable conditions of temperature 

 and moisture. 



As may be seen from figure 6, the adult male differs conspicu- 

 ously from the female. It is much shorter, measuring from about 

 2 to 2.5 millimeters in length, or approximately one-half that of 

 the female, and is more slender, its maximum width being from 

 one-twentieth to one-thirtieth of the length. The anterior end is 

 broader and not as rounded as in the female, and slightly in front 

 of the pointed tail end it possesses a curved transparent wing, the 

 bursa, with which females may be held. Near the center of this 

 bursa is located the opening of both the intestine and the reproduc- 



