THE CANADIAN ENTOMOLOGIST. 



isphere it extends across Europe, and in Asia, throughout Western 



;ria. 



Harp aim caliginosus Fab. The stridulation of this common beetle is 

 referred to in Ent. Amer., ii., 239, as not recorded previously and as a 

 discovery of Dr. Horn, and also that stridulation takes place only when 

 the beetle is at liberty, and can not be made to do so when handled. 

 This species and H pe?msylv aniens DeG. feed on ragweed (Ambrosia 

 artemisicefolia) when it is in bloom — here, in July, and both are exces- 

 sively abundant. Let the entomologist visit on a calm, sultry evening, 

 before sunset, some stubble field bordered by woods, when this weed is in 

 flower, and he will often witness a lively and by no means quiet scene ; 

 hundreds of the former and thousands of the latter will be seen mounted 

 on the weeds, each actively and intently employed in collecting the pollen 

 from the flowers, or licking some delectable morsel from the leaves and 

 occasionally evidencing its delight in a sonorous manner — a sudden 

 squeak — somewhat like the noise made by a steel pen scratching rough 

 paper ; and so intent are they on the business in hand as to be captured 

 before observing the approach of an enemy. 



Stridulation is effected in both by the beetles rubbing the large costre 

 of the wings against the elytra, these costse being coarsely transversely 

 rugose from the base to near the apex. Stridulation is readily produced 

 after death by pressing intermittently on the elytra, provided the costaj 

 are in a position to be brought in proper contact with them. 



H compar and H. longicollis are catalogued as varieties of H. penn- 

 sylvanicus, but curiously enough, though abundant, they do not seem to 

 have the same tastes, as I have never taken a single specimen of either 

 on ragweed, though carefully sought for. I strongly suspect they are 

 really three distinct species, notwithstanding the near approach in form of 

 some individuals, and certainly nothing is gained by the collector by 

 classifying them as varieties. 



Graphoderes fasciatocollis Harr. was considered to be the same as the 

 European G. cinereus, till separated by Dr. Sharp in his learned Mono- 

 graph of the Dytiscidae, p. 693 ; this separation is pronounced " unwar- 

 ranted " by Dr. Horn, Tr. Am. Ent. Soc, x., 280. Two primary points 

 of difference are given by Dr. Sharp ; the first, that t^e male of fasciato- 

 collis has " twenty-three " small pallettes on the anterior tarsus and twelve 

 on the middle, while that of cinereus has " about twenty-eight " on the 

 anterior and fourteen on the middle one ; the second, that in the former 



