4 ENTOMOLOGICAL NEWS [xxxii, '21 



flats between them, \\~hen collecting upon a gently rolling 

 surface, it has been repeatedly noted that a difference in alti- 

 tude of only a few feet may be sufficient to cause a change in 

 the number of specimens found, there being fewer on lower 

 ground where drainage would be imperfect. It also frequently 

 happens that a field located in lower ground surrounded wholly 

 or in part by slightly higher areas may be practically free of 

 damage, although the insects are present nearby in abundance. 



It has long been known that a prolonged dry spell in the 

 semi-arid regions caused practically complete disappearance of 

 Tenebrionidae from the surface of the ground. Notwithstand- 

 ing the fact that the beetles normally avoid low-lying damp 

 spots, yet showers form the most effective stimulus to bring 

 the adults to the surface from their subterranean cells in which 

 the pupal life has been passed. Such showers will be found 

 by the collector to be in direct ratio to the abundance of speci- 

 mens found. Adults leave shelter and run about just before or 

 just after a rain, and throughout the day during cloudy weath- 

 er, in the manner habitual to their twilight activities. 



Covering of soil. If the growth of vegetation is sufficiently 

 heavy entirely to cover and shade the ground, these insects are 

 present only in small numbers, whereas if the covering of 

 weeds, thistles, and debris is not too thick, the insects may 

 flourish in abundance. All of the different genera under con- 

 sideration are often found in greatest profusion under small 

 piles of Russian thistles (Salsola kali var. tcnnifolia Mey.) 

 which have been cut and piled in small heaps preliminary to 

 destruction by fire, or where thistles and other trash, blown by 

 high winds, have lodged along fence rows and other obstruc- 

 tions. They are usually present in greatest numbers beneath 

 piles of dried rather than green thistles. Both larvae and 

 adults can be found beneath loose straw around the edges of 

 wheat and in stockyards around shocks, wheat stacks, and piles 

 of threshed straw. Greater numbers occur beneath edges of 

 new straw piles than of those two or three years old. Elcodcs 

 are often congregated, sometimes in considerable numbers, 

 under dried leaves at the base of the common thistle (Cirsinni 

 lane eolat um Hill). Such habits might of course be used to 



