446 PROCEEDINGS OF THE NATIONAL MUSEUM 



Enemies 



In addition to unfavorable ecological conditions (including the 

 physical factors of wind, water, temperature, sunlight, etc.), the 

 Sisyridae, in fulfilling their role in the balance of nature, are subject 

 in all stages of their development to the attacks of predators ano 

 parasites (tables 5, 6). 



Family SiSYRIDAE 



Small, dull-colored spongilla-flies;^ larvae aquatic. 



Diagnosis (adult) : Compound eyes large, widely separated, ocell 

 absent; antennae setose, approximately one-half the length of fore< 

 wing, basal segment enlarged, flagellum moniliform and multisegv 

 mented; mandibles well developed, maxillary palpi 5-segmented ano 

 labial palpi 3-segmented with terminal segments expanded; prothoraa 

 broader than long, lateral margin without lobes; legs cursorial, for& 

 coxae elongate and free; abdomen cylindrical. Wings subequal, oval 

 apices usually rounded. Forewing: costal area narrow in general 

 particularly narrowed at base to about humeral cross-vein, thei 

 widened, and narrowed again just before pterostigma, costal cross; 

 veins usually simple, rarely forked, pterostigmal cross-veins numerous 

 poorly defined; humeral cross-vein not recurrent; Sc with apical enc 

 weak, sometimes appearing fused with Rl, at other times appearing 

 free to margin or atrophied before margin, and connected by a radiai 

 cross-vein; Rs separating from Rl near base of wing; Rs coalescec 

 with MA for a short distance, then separating, free stem of Rs witl 

 from one to two main branches; Rl, Cul and branches of Rs and Isl 

 usually with marginal forks, sometimes anal veins also, somewhas 

 variable in extent; Cul with almost parallel branches to margin; Cull 

 (usually simple, sometimes forked at margin) and usually thi'ee ana| 

 veins present; cross-veins few and specialized, gradates sometime 

 present. Hindwing: costal area narrow, cross-veins unforked, ptero 

 stigmal cross-veins numerous, poorly defined; MA coalesced wit 

 MP at base, then separating into a free, weakened, sometimes some 

 what sinuate, elongate basal section, eventually coalescing with E 

 for a longer distance than in forewing; Cu2 present and simple; few€; 

 cross-veins than in forewing; gradates sometimes present. Membran; 

 covered with microtrichia, longitudinal veins and costal cross-veir 

 with both micro- and macro trichia; trichosors present on distal poj 

 tions of outer and inner margins; a fringe of setae along margins 

 some thyridia also present; coupling apparatus consisting of a reduce 

 jugofrenate type; body covered with long setae. 



» Westwood (1848, p. 557) referred to the "spongilla insect" and Needbam (1901, p. 560) subsequent 

 suggested the common name of "spongilla flies." They have also been called "sponge flies." 





