38 Annals Entomological Society of America [Vol. X, 



nine approximately mature eggs at a time, the other eggs in the 

 ovaries being distinctly undeveloped. It thus seems impossible 

 for a female to deposit more than nine eggs during a single trip 

 below the surface of the water, assuming that she could with- 

 stand submergence long enough to deposit the already mature 

 or almost mature eggs, and it scarcely seems possible that the 

 sojourn below could be so long that undeveloped eggs would 

 have time to mature and be deposited also. Therefore, it seems 

 improbable that, in instances where as many as seventeen eggs 

 were found on a single petiole, all of them could have been 

 deposited at one time by the same female. It is true, as pointed 

 out, that the difference in the maturity among the larvae or 

 pupse on a single petiole is often not marked but it may be 

 that such a condition is due to the coincidence of the egg-laying 

 period of a large number of females in that particular locality, 

 a possibility which is borne out by the observation that in the 

 region studied during the past five summers it often happened 

 that many adjacent petioles contained larvae of approximately 

 the same degree of development. 



Development of Eggs. — Owing to the fact that the writer was 

 not able to secure the deposition of eggs in the laboratory, the 

 egg period is not definitely known. Collections of eggs showing 

 the least development were secured in the field, brought to the 

 laboratory, kept under approximately natural conditions, and 

 the last hatching dates recorded. This imperfect evidence 

 points to an egg period of about six to eight days. The only 

 noticeable external change which accompanies the development 

 of the egg is a darkening of the color which begins to appear 

 only a few hours before hatching. 



Not only does a definite and constant relation exist in the 

 position of the ends of the egg in the ovariole, but a similar 

 relation exists in the orientation and development of the larva 

 within the egg. The anterior end of the larva is invariably 

 developed in the rounded, blunt, concave end, i. e., the one 

 which is nearest the terminal filament while still within the 

 ovariole. Furthermore, in all of the specimens examined, the 

 ventral part of the larva is developed on the side opposite the 

 carinae and the dark, conspicuous mouth armature is curved in 

 the same direction. 



