882 CHARLES PAUL ALEXANDER 



at tip, with two teeth at about midlength. Maxilla with outer lobe greatly prolonged into 

 a flattened blade. Antenna cylindrical or clavate, with three Or four long papillae at tip. 

 Mentum not chitinized, in E. cinerea with a flattened rectangular plate on either side, this 

 armed with numerous hooks and spines. 



Pupa.- Cephalic crest of various shapes and sizes, very reduced in Eriocera spinosa. 

 Antennal sheaths of males of several species (E. spinosa, E. longicornis, E. cinerea) very 

 long, extending beyond end of wing pad. Pronotal breathing horns of various shapes, acutely 

 pointed in E. spinosa, short and blunt in several species. Head and thorax often wit'i 

 spines or tubercles on scape of antenna, on labrum, or (in E. spinosa) on face of eye; a 

 tubercle on scutellum (in E. longicornis), one on dorsum of second abdominal segment (in E. 

 spinosa). Abdominal segments with a conspicuous transverse armature of spines near 

 posterior margin. Lateral spiracles large, distinct. 



Eriocera is an extensive genus (including approximately 150 species) 

 of medium-sized to large- flies, most of which are tropical. The genus 

 has not been found in Europe, but elsewhere it is represented by a host 

 of species. The habits of the adult flies have already been noted (page 

 704). The immature stages are spent in sand or gravel near running 

 water, more especially along large streams. A more complete account 

 of the genus is given by Alexander and Lloyd (1914) and by Alexander 

 (1915 c: 148-152). 



The occurrence of the flies is somewhat local. During an entire summer 

 of collecting in Maine in 1913, the writer did not find a single specimen 

 of any species; and Dr. Dietz has stated that the only living individual 

 which he has found was a single male of Eriocera spinosa takeji in the 

 Pocono Mountains in Pennsylvania. On the other hand, the flies are 

 often found in countless numbers, and several species may be found 

 associated together. Thus, at Ithaca, New York, in the sandy gravel 

 along Cascadilla Creek, the immature stages of four species of Eriocera 

 and one of the closely related Hexatoma occur together in unlimited 

 numbers. 



The species of Eriocera may be separated by the following keys: 



Larvae 



1. Lobes surrounding spiracular disk obsolete or nearly so; a flat, chitinized plate with ser- 



rate margins on either side of mental region E. cinerea Alex. (p. 886) 



Spiracular disk surrounded by four slender lobes; no plate as described above on mental 

 region 2 



2. Very large (length 40-45 mm., diameter 4-5 mm.); spiracular disk with ventral lobes 



narrowly lined with black, inner ends of each forked, Y-shaped; lateral lobes narrowly 



\ lined with black, inner ends of marks expanded E. spinosa (O. S.) (p. 883) 



Smaller (length under 30 mm., diameter under 2.5 mm.) ; spiracular disk not marked 

 as above 3 



