184 Annals Entomological Society of America [Vol. IX, 



although a few larval cases were found, in part, composed of 

 fragments of leaves of Vallisneria, a fact which suggests that 

 this plant may be used for food. No evidence of feeding on 

 any of the water-lilies was observed. The larvae are active from 

 the moment of hatching and soon begin feeding, evidence of 

 which is the early appearance of yellowish matter in the 

 digestive tract. 



SUMMARY. 



Aquatic Lepidoptera are very limited in number and the 

 American species are little known. They rival other aquatic 

 insects in the character of their unique habits and adaptations. 

 Two species are considered in this paper. 



I. Nymphula maculalis Clem. 



1 . Eggs are deposited only on the lower, submerged surface 

 of the leaves of the yellow water-lily, Nymphcea americana, in 

 masses arranged in concentric rows. 



2. Egg masses, in the Douglas Lake region, are invariably 

 placed about the egg holes of the chrysomelid beetle, Donacia. 



3. Laboratory observations and experiments on females in 

 aquaria yielded the following data: (a) Eggs were invariably 

 deposited at night. (b) Eggs were invariably placed about 

 Donacia egg holes when the latter were available, (c) Oviposi- 

 tion may extend over five successive nights, (d) One female 

 may use several Donacia egg holes before oviposition ceases. 



(e) Maximum number of eggs laid by a single female was 617. 



(f ) In the absence of Donacia egg holes or other similar punctures 

 in the water-lily leaves, oviposition was usually delayed but 

 ultimately resulted in the deposition of small egg masses on the 

 lower side of the leaves at the margins. Egg masses were 

 deposited about artificial punctures and incisions of various 

 sizes and shapes, the dimensions of which apparently had little 

 to do with the selections. 



4. The egg period is about eleven days. There is a definite 

 and constant orientation of the eggs in the mass since the heads 

 of the larvae invariably develop in the ends of the eggs nearest 

 the leaf puncture. 



5. The larva in the first instar is devoid of tracheal gills and 

 respiration is apparently cutaneous. 



