12 BULLETIN 838, U. S. DEPARTMENT OF AGRICULTURE. 



On the second-stage female larva are to be found the small tri- 

 locular pores scattered over the body, and from 40 to 75 of the large 

 tubular ducts on the margin and dorsum (particularly on the ab- 

 domen). The pores of the second-stage male larva are of two types: 

 The small quinquelocular type which are found all over the body, 

 and tubular ducts similar to those of the second-stage female larva, 

 but much smaller and less conspicuous, found mostly on the margin. 



The pores and ducts of the adult female are of the trilocular and 

 tubular types, the first scattered over the body and the latter occur- 

 ring on the margin and dorsum of the body, much the same as in the 

 second-stage female larva. 



Small spines (PL Y, Z>, 3) are present on all these stages. Viewed 

 from above, these spines are likely to have the appearance of cir- 

 cular pores, but can be soon distinguished by altering the focus of 

 the microscope. 



LIFE HISTORY AND HABITS. 



In the early winter adult females are found containing a few eggs. 

 The eggs increase in number and by early spring from 30 to over 100 

 may be found within each female. During this time the females 

 have increased considerably in size and have become quite heavily 

 chitinized on the anterior half of the body. 



OVIPOSITION. 



The embryos in the eggs develop within the body of the female 

 until they are about ready to hatch, when they are expelled (PL IV, 

 E) . The female is well surrounded by a cottony secretion, but when 

 oviposition is begun the tip of the abdomen is drawn in, leaving a 

 space in which the eggs may remain until hatched. After hatching, 

 the larvae are usually able to find an exit between the cotton and the 

 surrounding bark. 



Each female is capable of laying 50 to 100 or more eggs. The 

 greatest number of eggs that has been found within a female at any 

 one time is 105. The eggs are laid slowly, covering a long period of 

 time. They are laid during the warmer part of the day at intervals 

 of 7 to 70 minutes. After laying a series of 5 to 10 eggs, the female 

 ceases oviposition for a day or so and then resumes it. 



Most of the embryos in the eggs are deposited tail first, about one- 

 sixth being deposited head first. The head end of the embryo is 

 evidenced by the two black eyes which are visible through the egg 

 membrane. By a series of contractions of the abdomen, the egg is 

 forced out until entirely free from the body of the adult. These eggs 

 are oblong oval when first deposited, but flatten out somewhat be- 

 fore the rupturing of the membrane occurs. 



