OF WASHINGTON. 133 



and G. interrogationis. Mr. Hubbard replied that he had not 

 observed the hatching of the eggs, but that he suspected that this 

 method is followed, since in egg-sticks preserved in alcohol he 

 observed that the embryo is further advanced in the top eggs. 



Dr. Gill asked if there is any especial modification of the ovi 

 positor. He thought there must be such a modification to en 

 able the moth to lay such a peculiar egg mass. Mr. Hubbard 

 said that no such modification had been found. Mr. Schwarz 

 stated that the moth is much shorter than the egg mass, and that 

 in his opinion the stick must have been bent and afterwards 

 straightened by either the moth or its own erectile power. Prof. 

 Riley thought that a membranous extensile ovipositor might 

 exist by which the act of oviposition could readily be accom 

 plished. Mr. Ashmead thought that the abdomen itself might 

 be sufficiently telescopic to produce the result. Dr. Stiles 

 thought that the necessary pressure to produce the compact stick 

 might be brought to bear in the ovarian tubules. Prof. Riley, 

 on the contrary, considered that the string was produced by 

 purely external mechanical effect. Dr. Stiles, in reply, said that 

 the eggs of insects as well as other animals are undoubtedly given 

 their shape to a considerable extent while still in the ovary, in 

 which Dr. Gill agreed with him. Mr. Howard said that the 

 masses must represent the ripe products of several ovarian 

 tubules, and that these could hardly be joined together until 

 after they had passed down the oviduct proper beyond the en 

 trance of the accessory glands, the secretion from which joined 

 them together, and, in fact, produced a stick. 



Mr. Schwarz asked if the cactus plants could not be saved 

 easily by the examination of the plant and picking off the egg- 

 sticks. Mr. Hubbard replied that he had saved a number of 

 choice plants in this way, but that it was a very considerable 

 task, and that during the month of May the plants had to be 

 gone over every morning. Some varieties of Opuntia, he said, 

 are so thick skinned that the young larvae cannot penetrate them. 

 Occasionally, however, larvae are found in these varieties, having 

 entered by means of artificial punctures or wounds. 



Prof. Riley stated that he had reared the moths many years 

 ago in St. Louis. It is the largest Phycitid which we have, and 



