August, 1944 



Ross: Caddis Flies of Illinois 



13 



Fig. 12. — Range map of Cheiimatopsyche Fig. 13. — Range map of Oecetis inconspicua, 



lasia. the commonest North American caddis fly. 



includes those whose range centers roughly 

 in or near Illinois; the second those touching 

 Illinois on the outskirts of their range. 



Ranges Centered in Illinois 



Widespread Species. — Some of the com- 

 mon Illinois species of caddis flies have a 

 range which occupies alrnost the entire con- 

 tinent. Examples include Oecetis incon- 

 spicua, fig. 13, and avara, CJieumatopsyche 



campyla and aualis and Hydroptila hamata. 

 The first four of these are exceedingly com- 

 mon in the central and eastern states and 

 occur in scattered collections westward to 

 the Pacific Coast. 



Central States Species. — Conspicuous 

 examples of this set are some of the caddis 

 flies inhabiting the large rivers typical of 

 this part of the country. Hydropsyche sirnu- 

 lans and orris are two such species; they 

 have overlapping ranges, fig. 14, and the 



Fig. 14. — Range map of Hydropsyche simulans and Fig. 15. — Range map of Hydro- 



orris, psyche aerata and phalerata. 



