162 Annals Eyitomological Society of America [Vol. IX, 



minal abdominal segment is elongated, cone-shaped, movable, 

 bent ventrad, and bears a long, protrusible ovipositor. Thus it 

 is possible for the female to deposit eggs from the top of the leaf 

 by clinging at the margin of the hole and extending the ovipos- 

 itor around the edge to the lower surface of the leaf. It also 

 appears that the sixth concentric row of eggs in an egg mass 

 represents the limit of extension of the abdomen and ovipositor. 

 A number of experiments were performed in order to secure 

 further data on egg deposition. In each experiment, a single 

 female, fresh in appearance and bearing evidences of recent 

 emergence from the pupa, was captured in the field, brought 

 to the laboratory, and placed in a well-lighted aquarium in 

 which a yellow water-lily leaf, bearing no Nymph iila eggs but 

 having one or more Donacia egg holes, was floated on water. 

 Frequent examinations were made of each aquarium during 

 the day and the early part of the night. The results, based 

 upon a number of such experiments, are as follows: 



(1) Deposition of eggs invariably occurred at night. 



(2) Eggs were deposited only about the Donacia egg holes. 



(3) A female may deposit eggs for five successive nights before oviposition 



ceases. 



(4) Donacia egg holes, devoid of Donacia eggs, were sometimes completely 



surrounded by six concentric rows of eggs of N. maculalis. 



(5) An egg mass, deposited during one night, was sometimes covered, in part, 



by a second layer of eggs deposited on a succeeding night. Apparently, 

 the deposition of one egg mass on another was an abnormal action, due, 

 possibly, to laboratory conditions, although, aside from the limited 

 space, the conditions in the aquarium resembled those of the natural 

 environment as nearly as possible. Egg masses collected in the field 

 invariably showed but a single layer. It is conceivable that such 

 a reaction might result from the total reduction of available space 

 about the Donacia egg holes, but experiments showed that it occurred 

 when the same leaf contained holes which afforded abundant space. 



(6) A single female usually utilized several Donacia egg holes before the egg 



laying period ended. 



(7) The maximum number of eggs laid by a single female was 617. 



The method of egg deposition in the absence of Donacia egg 

 holes was of interest in this connection. Fresh, vigorous 

 females, captured in the field, were placed in aquaria under 

 conditions simulating the natural ones as nearly as possible. 

 Each aquarium contained yellow water-lily leaves representing 

 one of the following conditions: (1) entire leaves containing no 

 Donacia egg holes ; (2) leaves containing artificial holes, varying 

 from narrow slits to circular holes, all of various dimensions; 

 (3) pieces of leaves containing no holes and having smooth-cut 



