90 RESULTS FROM GIPSY MOTH PARASITE LABORATORY. 



truly respiratory organ, as we think it must be. This change is per- 

 haps correh\ted with the more ravenous appetite of the parasite in 

 the last two stages of its larval life, and also with the gradual dis- 

 appearance of the blood and lymph of the host. With the disappear- 

 ance of the fluids of the host, the tail as a blood gill must neces- 

 sarily become useless, as it is fitted for life in a fluid medium only. 

 Nor does it seem possible, for much the same reason, that the larva's 

 whole supply of oxygen is gained by osmosis through the integimient 

 of the body itself, for as the larva grows older the integument be- 

 comes thicker and tougher, especially in the last stage. The only 

 alternative left is to consider that the oxygen is derived from the 

 comparatively enormous amount of food taken in during this period, 

 and that it is absorbed by the blood of the larva through the walls 

 of its digestive tube. In other words, if the larva stopped feeding it 

 would not only starve but also suffocate. Toward the end of the third 

 stage, however, when the host is nearly or possibly not entirely 

 consumed the stigmata become open, and the larva is able to breathe 

 air directly, as it certainly does after leaving the host to spin its 

 cocoon. 



THE COCOON. 



The cocoon has been aptly described by Dr. L. O. Howard (1897) 

 in his bulletin on the parasites of the white-marked tussock moth, and 

 we take the liberty of transcribing his words here : " The cocoon is 

 rather long ellipsoidal, averaging 7.5 mm. in length by 2.8 mm. in 

 greatest diameter. It is composed of two distinct coverings, the outer 

 one of weak, close-spun, crinkly, gray, or grayish-brown silk, readily 

 peeling off in a sheet, and the inner one close, tough, parchmentlike, 

 dark brown in color, wnth golden reflections, of the type common 

 among the Ophioninse." 



RESULTS OF THE DISSECTIONS OF HYPHANTRIA DURING THE 



FALL OF 1910. 



During the late summer and the fall of 1910 a large series of col- 

 lections of the fall web worm {Hyphantria cunea Drury) was brought 

 together at the Gipsy Moth Parasite Laboratory, and an extensive 

 study made of its parasites by means of dissection and rearing work. 

 Most of the work was conducted by Mr. J. D. Tothill, who kindly 

 turned over to the writer, together with his notes, the series of larvae 

 of Limnerinm, that were found during the course of the dissections. 

 Inasmuch as another species of Limnev'ium is found attacking the 

 fall webworm in Massachusetts rather abundantly, the collection of 

 larvae may have included L. pilosulum as well as validuni, but the 

 most careful scrutiny of the larvae, all of which were mounted in 

 balsam and in the first stage, failed to reveal any characters to sepa- 



