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weakly about. The song of Cicada marginata, resembling that 

 of the periodical cicada, was heard; and in the twilight came 

 the penetrating shrilling of Conocephalus robustus, and the rat- 

 tling note of the male of Heliocheilus paradoxus, as moths of 

 the latter species danced in groups here and there. 



The abundant wild flowers were visited by large numbers 

 of bees, wasps, and other aculeate Hymenoptera, many of which 

 were species rarely or never seen on the prairie,— Dielis plu- 

 mipes, for example, — probably associated with the unusual flora. 

 Families which nest in sand were well represented, such as the 

 Larridw, which capture young Ortkoptera to provision their 

 nests, the Bembecidce, which use flies for this purpose, and the 

 bee family Colletidce. In fact, this kind of region seems partic- 

 ularly favorable to the development of these insects in great 

 numbers and variety because of the undisturbed ground and 

 vegetation in addition to the character of the soil. Hoppner 

 ('01) shows that similar conditions prevail in a tract of dune 

 sands along the Weser valley in Germany, finding there six 

 characteristic local species of bees, and three others more 

 abundant there than elsewhere, the total list including two 

 thirds of all the bees found in northwest Germany. To de- 

 velop this subject for our district would require vastly more 

 time than was available. 



The insects associated with some of the more common 

 plants of the sand region may next be grouped under their re- 

 spective plants. 



Mesadenia atriplicifolia. — This may well head the list of 

 host plants, with its interesting insect guests. On the flowers 

 of scattered clumps of these plants were two far western spe- 

 cies, a large tenebrionid (Epitragus acutus) and a long-legged re- 

 duviid (Zelus sodas), also Lygwus bicrucis, and, upon the stems, 

 Languria bicolor, the larvae of which burrow in the stems. 



Opuntia humifusa. — This cactus was usually abundant, and 

 sometimes supported flourishing coloniesof Pentatoma juniperi- 

 na. It was also responsible for the presence of the bright-yel- 

 low-striped chunky little syrphid fly, Volucella fasciata, seen 



