SIMULIUM. 



185 



species, probably of quit-e different families, included under tlie 

 general title of " eye fly," as from personal experience (but speaking 

 from memory) I think tliat both small Ceratopogonin.b and even 

 minute Empid.^ have been brought to me as " eye flies." 



Fig. 23. — Early stages o^ Simulimn : a, group of larvre ; b, larva oi S.ornaium, 

 Mg., a European species; c, group of pupa3 ; (/, pupa in its case ; c, oupa 

 (after Miall). 



Life-history. The larva of Simulium is aquatic, living mostly in 

 mountain streams, in the stems of water-plants (PheUandrium, 

 Siuin, etc.), or attached by the tail-end to rocks covered by swiftly 

 running water, their bodies being held vertically. Their chief 

 requirement is that the water shall be well aerated, but the water 

 itself need not necessarily be pure, as the larva of S. reptans has 

 been found in Europe swarming in streams contaminated by sewage. 

 The food of the Simulium larva is microscopic, diatoms and 

 desmids. The power of attachment is very considerable, its 

 swimming power very weak. It is cylindrical, soft-skinned, 

 nari'owed in the middle, eulai'ged at the end, possessing tv.c pairs 

 of eye-spots, two large fan-like branched antennae, and on the 

 underside of the first thoracic segment a foot-like protuberance 

 with bristly booklets or teeth ; this structure forms a sucker and 

 is constructed by the coalescence and development of the first pair 



