CHAPTER 11 



Aquatic Lepidoptera 



By W. H. Lange, Jr. 

 University of California, Davis 



The Lepidoptera number more than 100,000 described 

 species and are characteristically terrestrial in their 

 habits. However, there are a few families, including 

 the Cossidae, Cosmopterygidae, Yponomeutidae, Arc- 

 tiidae, Phalaenidae, Tortricidae, Tineidae, Nepticuli- 

 dae, Pyralidae, and Sphingidae, containing species 

 capable of aquatic or subaquatic existence either in 

 their immature forms or as adults. The Pyralidae, and 

 particularly members of the subfamily Nymphulinae, 

 have met the challenge of an aquatic existence very 

 successfully. For this reason the present discussion 

 will concern itself primarily with this group. Acentro- 

 pus niveus (Oliv.), in the pyralid subfamily Schoeno- 

 biinae, is included in the keys because of its true 

 aquatic existence. It is probably a recent introduction 

 in the United States. 



CLASSIFICATION 



The recent paper by Lange (1956) is the first attempt 

 to classify our North American genera of aquatic 

 moths on a morphological basis. Before this most 

 investigators placed our species in either Nymphula 

 or Cataclysta (Elophila). The check list of McDun- 

 nough (1939) lists ten genera in the aquatic pyralids 

 (Nymphulinae) of which Hydropionea, Geshna, Dia- 

 thrausta, Stenoides, Piletocera, and Eurrhypara are 

 pyraustine and not nymphuline, leaving the genera 

 Nymphula, Arabia, Cataclysta, and Oxyelophila. Klima 

 (1937) lists ninety-six genera in the Nymphulinae, 

 but many will be found to belong elsewhere when a 

 complete study is made. Schaus (1924, 1940, and other 

 papers) has named many of the tropical American 

 species in the Nymphulinae. 



The classification of the North American Nymphuli- 

 nae in the past has been based upon the work of many 

 early European students. A few of the more salient 

 references to North American Nymphulinae are those 

 of Grote (1880, 1881), Meyrick (1890, 1895), Hampson 

 (1897, 1906), and Dyar (1906, 1917). Forbes (1923) 

 gives keys to the adults and immature forms of the 

 eastern species. 



Our known California species of true aquatic moths 

 belong to the genera Synclita, U sinyeriessa, and Para- 

 rgyractis. In addition, a single larva of the genus 

 Parapoynx has been taken. 



BIOLOGY 



On the basis of ecology and morphology the North 

 American Nymphulinae can be divided into the Nym- 

 phulini, or the typical plant-feeding forms, and the 

 Argyractini, or rock-dwelling forms that feed on algae 

 and diatoms. 



The immature stages of many of the plant-feeding 

 species are fairly well known in the United States, 

 but the rock-dwelling forms offer a virgin field for 

 research. Packard (1884) and Hart (1895) were among 

 the first in this country to study our aquatic, plant- 

 feeding caterpillars, followed by Forbes' (1910) 

 studies at Lake Quinsigamond and a study of a case- 

 forming species on Lemna (Forbes, 1911) 1 . The 

 investigations of Welch (1914, 1915, 1916, 1919, 1922, 

 1924) and Welch and Sehon (1928) have added greatly 

 to our knowledge of the biology and respiratory mech- 

 anisms of the plant-feeding aquatic moths. Frohne 

 (1938, 1939a, 19396) discussed the role of higher 

 aquatic plants in relation to the food cycles of insects 

 and particularly in reference to the food habits of 

 several semiaquatic moths related to those under 

 discussion. 



Berg (1949, 1950) greatly increased our knowledge 

 of the various aquatic caterpillars associated with 

 plants of the genus Potamogeton. The work of Berg 

 and Frohne was continued in investigations by McOaha 

 (1952, 1954), covering the limnological and biological 

 relations of insects to a number of species of flower- 

 ing plants. Pennak (1953) gives one of the more 

 recent reviews of aquatic Lepidoptera, placing them 

 all in two genera, Elophila and Nymphula. 



There is considerable variation in the biological 



I believe this record applies to Neocataclysta magnificalis 

 (Hub.) 



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