1916] Biology of Aquatic Lepidoptera 181 



Only incidental observations on the enemies of this species 

 were made in this connection. It is probable that the possession 

 of a case in the larval and pupal stages is a provision whereby 

 considerable protection is afforded. The larvae occur in situa- 

 tions which are rich in predaceous animals of several kinds and 

 there is no reason to suppose that such fleshy larvae would be 

 exempt from attack. One of the robber-flies, common in the 

 Douglas Lake region, preys on the adult and specimens of the 

 latter have been taken with adult N. maculalis in their claws. 

 Although this robber-fly is a vigorous enemy, it seems probable 

 that the nocturnal habit of the moth prevents greater fatality 

 from this enemy. 



Nymphula icciusalis Walker, 



Early Stages. 

 Nymphula icciusalis is abundant on the north shore of 

 Douglas Lake about the bays, beach pools, and inlets, all of 

 which contain quantities of Potamogeton, Vallisneria, and other 

 aquatic plants. By confining females in aquaria containing 

 the leaves of several aquatic plants, egg masses were easily 

 secured and the process of hatching and the early development, 

 of the larva were observed. Since the early stages of the life 

 history have not been described, the following data have been 

 included in this paper. Packard ('84, p. 824) figured a larva,, 

 which he supposed to be N. icciusalis. Forbes ('10, pp. 225-6) 

 reared a single larva through to maturity and reported close 

 correspondence of data with those of Packard, but made no- 

 mention of the eggs or early larval instars. Miller ('12, pp. 

 127-134, 245) made some observations on this species, described 

 some of the activities of the larvae, made slight mention of the 

 pupa and of the eggs, and described the full grown larva irt 

 considerable detail. 



The Egg. 

 Place and Method of Deposition. — The following data were 

 taken from egg masses deposited by females in the aquaria and 

 from numerous egg masses taken in the field. Egg masses from 

 both sources were laid on the leaves of Potamogeton natans. In 

 aquaria containing only Nymphcea americana, females, after- 

 some delay, deposited eggs on the leaves of this plant in the 

 characteristic way but this was evidently not a normal reaction. 



