172 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.48. 



over is mainly that of the Upper Sonoran life zone. This of course 

 merges into that of the transition zone on the slopes of the mountains 

 and foothills. 



That the insect life of this semiarid region is surprisingly abundant 

 is attested by the large amount of material secured within a very 

 limited period of time. That is to say, about 25 days, which period 

 was materially reduced by inclement weather to not more than 20 

 days actual collecting. 



Some 30 or more species of Tachinida? were secured; several of 

 these represent genera or species new to science. The most remark- 

 able of these is the form described below as Neodichocera tridens, new 

 species, giving rise to a new genus. This is a fissicorn tachinid, and 

 the first species recorded from North America possessing three divi- 

 sions of the third antennal joint. 



The most abundant families of diptera found in the region explored 

 are Bombyliidse, Asilida?, and Tachnida? in the order named. The 

 Bombyliidse are the most generally distributed, with the Asilidse 

 second. On the other hand, the Tachinidse, while abundant in spe- 

 cies, are apparently much localized in distribution. Also, practically 

 all of the species and individuals collected, excepting those from the 

 immediate vicinity of water, are of small or medium size. Thus in 

 the vicinity of the Red River, a mere brook during the warmer part of 

 the summer, several large specimens of Gonia capitata were taken. 

 Near irrigation ponds specimens of Phorocera claripennis were col- 

 lected which are at least 3 times as large as most individuals collected 

 on the dry mesa. Specimens secured upon the slopes of the foot- 

 hills and also on the summit of Eagle Tail Mountain, where the pre- 

 cipitation is considerable, average much larger in size than those from 

 the plains. This may be due to a greater abundance of host insects 

 or to the presence of host species which do not exist on the more arid 

 plains. Specimens of Musca domestica were seen near the summit 

 of Eagle Tail, miles away from human habitations. One specimen 

 of Myiospila meditabunda was also taken about 100 feet below the 

 summit. 



Stomoxys calcitrans is abundant, widely distributed and extremely 

 troublesome to man and beast during the warmer parts of the day. 

 Strange to say, hordes of hungry mosquitoes sometimes appear after 

 one of the furious rains which occasionally visit the plains. These 

 follow one about in the burning sunshine and bite during the daytime, 

 but are not very troublesome at night within the tents. No blood- 

 sucking diptera other than those mentioned above were found. 



The writer is greatly indebted to Mr. V. L. Wildermuth and other 

 members of the range caterpillar camp for notes, specimens, and 

 many courtesies extended and offers his hearty thanks to them one 

 and all. 



