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Illinois Natural History Survey Bulletin 



Vol. 23, Art. 1 



one much larger than the right, with a 

 large dorsal projection from the lateral 

 margin, this projection somewhat thumb 

 shaped and very high; a single brustia is 

 present; and the row of teeth is even. The 

 right mandible has only a slight flange on 

 the dorsal lateral portion, a large tooth 

 dorsad of the regular series, the regular 

 series itself composed of three or four ir- 

 regular teeth. 



Adults. — Unknown. 



Larvae of this distinctive form have been 

 taken in small numbers at the mouth of 

 Union Spring, a small underground river 

 in the Ozark Hills near Alto Pass, Illinois, 

 as well as at Parksville, Tennessee (see 

 Aphropsyche aprilis) . Efforts to rear this 

 species have so far been unsuccessful, but 

 such a large proportion of the genera of the 

 Hydropsychidae are known that there seems 

 good likelihood of this species proving to 

 belong to one of the rare primitive genera 

 such as Aphropsyche. 



Diplectrona Westwood 



Diplectrona Westwood (1840, p. 49). Geno- 

 type, by original designation: Hydropsyche 

 flavo-maculata Stephens nee Pictet = Diplec- 

 trona Jelix McLachlan. 



Only a single species of this genus occurs 

 in Illinois. In addition to this one species, 

 californica is known from the western 

 states, and another species, doringa, has been 

 described from New Hampshire. Dr. Milne 

 informs me that the holotype of the latter 

 may be lost; hence no diagnosis of the geni- 

 talia can be given. 



Diplectrona modesta Banks 



Diplectrona modesta Banks (1908^, p. 266); 

 cf , 9. 



Larva. — Length 15 mm. Color of head, 

 thoracic shields, and legs dark reddish brown 

 to almost black; if reddish brown, the head 

 has several indistinct darker markings. 

 Head convex, frons sharply widened at 

 middle, fig. 304. Mandibles sharp and 

 stocky without lobes on the lateral margin, 

 and with the teeth of both mandibles irregu- 

 lar in size, fig. 286. Abdomen with a mix- 

 ture of short, appressed pubescence and 

 erect, flattened hairs; each segment has in 

 addition two pairs of tufts of a few long, 

 slender hairs. 



Adults. — Length 12-14 mm. Color of 

 head, body and wings dark brown with a 

 reddish tinge, the wings without mottling 

 or pattern. Male genitalia composed of 

 quite simple parts, fig. 339: tenth tergite 



Fig. 339. — Diplectrona modesta, male genitalia. 



divided into a mesal and a lateral pair of 

 lobes; claspers with basal segment very long, 

 apical segment short and narrow; aedeagus 

 tubular and curved, with sharp sclerites set 

 in the apex. 



We have taken this species commonly in 

 two spring-fed streams in Illinois, one of 

 them at Elgin in the northern part of the 

 state, the other at Alto Pass in extreme 

 southern Illinois. Scanty Illinois collections 

 have been made along other small spring- 

 fed streams, also. The adult emergence is 

 confined to late spring and early summer. 

 May and June. In more northern states 

 adults have been taken as late as July, and 

 in southern states as early as the month of 

 April. 



The species ranges throughout the wood- 

 ed portions of the eastern states and ex- 

 tends through the Ozarks into Oklahoma. 

 Throughout its range it frequents rapid, 

 clear brooks and streams. We have records 

 for Arkansas, Florida, Georgia, Illinois, 

 Indiana, New Hampshire, New York, 

 North Carolina, Oklahoma, Ontario, Penn- 

 sylvania, South Carolina, Tennessee and 

 West Virginia. 



Illinois Records. — Alto Pass, Union 

 Spring: May 31, 1938, B. D. Burks, 2 

 larvae, 1 ? ; May 12, 1939, Burks & Riegel, 

 1 larva, 1 $ ; May 23, 1939, Ross & Burks, 

 many larvae; May 29, 1939, Burks & 

 Riegel, 1 5 ; May 14, 1940, Mohr & Burks, 

 3 larvae; May 26, 1940, Mohr & Burks, 

 many larvae, 2 5,29; May 31, 1940, B. D. 

 Burks, many larvae; June 20, 1940, Mohr 

 & Riegel, 1^. Elgin, Botanical Gardens: 

 April 19, 1939, Burks & Riegel, 1 larva; 

 May 9, 1939, Ross & Burks, 4 pupae, 3 



