Moore AND HuNGERFORD : Water Insects. (^y ^^/ 



A. Antennal segment 1 longer than 2 plus 3. Eyes protuberant. Middle and 

 hind femora about equal in length. Venter of sixth abdominal segment 

 in male with median longitudinal fossa. The seventh with a longitudinal 

 ventral carina. Gerris conjormis Uhl. 



AA. Antennal segment 1 shorter than 2 plus 3. Eyes not protuberant. Middle 

 femora shorter than hind femora. Venter of sixth abdominal segment in 

 male without fossa and seventh segment not carinate. 



Liinnoporus rufoscutellatus Latr. 



In addition it may be stated that L. rufoscutellatus Latr. is a 

 more slender species, and that it is usually of a russet color. Gerris 

 conjormis Uhl. has the anterior part of the pronotum bearing two 

 prominent papillae and well-elevated callosities. 



It would seem somewhat of a question whether these two species, 

 having in common genital characters and exceptionally long femora, 

 can be placed in separate genera upon the antennal character alone. 

 Structurally they are more nearly congeneric than G. remigis Say 

 and G. conjormis Uhl. The latter belongs with L. rujoscutellatus 

 Latr., and the generic characters of Limnoporiis should be revised. 



resume. 



In brief resume of the above collecting notes, it may be said that 

 the southern Utah desert affords extremely interesting problems for 

 the student of water life. The light' annual rainfall, the isolation of 

 the pools and the nature of the water they contain, lend interest to 

 the study of the resident population of the waters. The collections 

 here reported represent the complete insect population of the various 

 pools surveyed. One isolated little spring-fed pool, the size of a 

 washbasin, contained three Notonecta insulata Kirby, and no other 

 insects. Another little rain-filled "tank," less than two feet in diam- 

 eter and a foot deep, located high up on the sloping wall of a canyon, 

 contained seven water boatmen, Arctocorixa abdominalis Say, and 

 not another insect. The scant annual rainfall of from five to ten 

 inches, with the exceptionally light fall in April, May and June, 

 works against a large population of aquatics. The water bugs 

 thus utilize every available supply of water. The pools contained 

 the corixids, notonectids and dytiscids, while the striders were found 

 on the springs more commonly than upon the "tanks." The pres- 

 ence of winged species in places remote from permanent water is 

 readily understood. The finding of eight Gerris orba Stal, all 

 winged, upon a rain-filled "tank" and forty-seven specimens of the 

 same species along the Yampa river, all apterous, is worthy of note.* 



* An interesting note on the factor regulating wing development is suggested by collect- 

 ing notes on Microvelia macgregori Kirk, in New Zealand by Mr. J. G. Myers, in the New 

 Zealand Journal of Science and Technology, vol. V, pp. 6 and 7. He writes that his col- 

 lections of this insect in the lowlands have been almost entirely apterous forms, while at an 

 altitude of 4,500 feet every capture was winged. 



