72 Annals Entomological Society of America [Vol. I, 



Among Hemiptera we have numerous cases of subterranean 

 adaptation, the most of the Cicadas, the root inhabiting Ful- 

 goridae, Cercopidse, Membracidse, and the highly specialized 

 underground species of Aphids and the burrowing Cydnidas 

 showing a drift in this direction. The Cicadidas are extremely 

 specialized for such life, and the nymphal stages profoundly 

 modified, showing a long ancestry of underground life. Among 

 the Fulgorids, Membracids and the Cercopids it occurs in isolated 

 forms and in these is in most cases of recent origin. Among the 

 Aphids many species of Rhizobius, Pemphigus and Schizoneuia 

 show this adaptation, often greatly complicated with association 

 with ants and by alternation of food plants or different root and 

 leaf feeding forms. In every case, however, there is the best 

 of evidence of the derivation of these root living forms from an 

 ancestry that lived only above ground, and hence a clue to their 

 systematic relationships is easily found. 



The ant lion is a special case of adjustment and a striking con- 

 trast to the aquatic and terrestrial members of its order. In the 

 construction of its pit-falls it shows a plan of underground life that 

 differs strikingly from that of any other insect and is so distinct 

 that it may be considered a good family character. 



In Coleoptera the underground habit is distributed among 

 many dift'e:ent families, but is especially characteristic of the 

 Scarabceid^e in a large section of which the underground con- 

 dition prevails for all but a short period of adult life. Here there 

 is a very distinct and extreme adaptation both in the matter of 

 food and adjustment to soil that fits them for this condition. 

 Among the flies we have the burrowing larvse of the crane flies 

 and the Bibionidas. 



Among the butterflies and moths we have but little adaptation 

 to underground life aside from the burrowing into the ground 

 for the purpose of pupation, but cut worms and sod worms spend 

 a considerable portion of their larval life in the soil, though 

 feeding for the most part above ground. The bees, ants and 

 wasps present us with a number of extreme forms of underground 

 habit, but this is in many cases associated with community life. 

 In fact community life seems very likely to have originated in 

 nearly every case from the insects which had adapted themselves 

 to this sort of existence. Some sort of protection such as cavities 

 in the ground or in rocks or trees may have been an essential 

 factor in the development of community life. 



