CONTRIBUTION TO THE BIOLOGY OF CERTAIN 

 AQUATIC LEPIDOPTERA.* 



Paul S. Welch. 



Insects of the order Lepidoptera are so pre-eminently 

 terrestrial in organization and habit that the existence of 

 aquatic species is not commonly known, even among biologists. 

 Information concerning American forms which inhabit the 

 water is meager and only a few of their remarkable adaptations 

 have been described. Klapalek and Griinberg ('09, pp. 96-159) 

 discuss sixty species and varieties, which they consider as 

 aquatic, from the fresh waters of Germany and there is reason 

 to believe that ultimately the American aquatic species will be 

 found to exceed that number. During the summers of 1911-15 

 the writer made some studies of the Lepidoptera of Northern 

 Michigan in connection with which special attention was given 

 to the aquatic group. The data, .which form the basis of this 

 paper, were secured in the immediate vicinity of Douglas Lake, 

 in the extreme northern part of the Southern Peninsula. Cer- 

 tain portions of the margins of this lake are rich in aquatic 

 vegetation and afford good breeding grounds for a considerable 

 variety of aquatic animal life. Adults of five species of the 

 genus Nymphula (Welch, '15, p. 118) were found in some 

 abundance about the protected bays and beach pools. This 

 genus is unique in being one of the very few groups of Lepidop- 

 tera which include species having aquatic stages in the life 

 history. Of the species of Nymphula known to occur in North 

 America, six are aquatic in some or all of the immature stages. 

 The larvae of several other species are not known, but it is 

 probable that they, too, will be found to be aquatic. 



In the past, generic divisions have been made in the group 

 of species now included under Nymphula, based mainly on 

 certain structural characters of the larv«. Those species having 

 tracheal gills in the larval stage were assigned to a separate 

 genus, Paraponyx, sl name still retained by some foreign workers. 

 In this paper, the writer follows the present American practice 

 of including the group assigned to Paraponyx, together with 

 others, under the genus Nymphula, even though two distinct 

 types of larvae are thus involved. 



*Contribution from the University of Michigan Biological Station, No. 33, 

 and the Department of Entomology, Kansas State Agricultural College, No. 16.. 



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