136 ORGANIC EVOLUTION 



the habits of the imitating form. The drone-fly, for example, 

 which imitates a honey-bee, has the same kind of buzzing 

 flight, and, when standing, occasionally teeters its abdomen 

 up and down, as is characteristic of the bees and wasps. 

 Some of these mimicking flies even protrude and withdraw 

 the tip of the abdomen, as does an angry bee or wasp, 

 making the imitation in habit as well as in form and color 

 as perfect as possible. 



At Wood's Holl one summer, while collecting insects 

 from the blossoms of the common milkweed, I was struck by 

 the resemblance of a moth to the large metallic blue wasp. 

 When the moth was at rest upon the milkweed blossoms, 

 this resemblance was not marked, but as one approached at 

 all near, the moth sprang into the air, flying with a peculiar 

 buzzing flight that seemed at once to transform it into a 

 wasp. The blue wasps were common upon the same blos- 

 soms, and the deception was very perfect. As these moths 

 are keen-sighted and easily startled, they must rarely be cap- 

 tured while at rest, and when flying they are likely to be let 

 alone by insect-eating birds and dragon-flies. In the Alle- 

 ghany Mountains I have found a large, blue-back longicorn 

 beetle, which when in flight closely resembles one of the blue 

 wasps. We have an American moth which similarly resem- 

 bles a bumble-bee, only in this case the resemblance is almost 

 as noticeable when the moth is at rest as when it is in flight 

 (Plate 70, O). The body has the same shape, is banded with 

 yellow, and is covered with similar long yellow hairs ; the 

 wings also are very different from those of most moths, 

 having lost most of their scales and being transparent, like 

 the wings of a bumble-bee. Many other moths mimic the 

 stinging Hymenoptera (Plate 70, L, M, N). 



