108 NATURE SKETCHES IN TEMPERATE AMERICA 



live, boring insect larvse have opened channels into the live 

 trees, through which the oak sap pours out, wetting the bark. 

 This comes in proper time, as food for the beetles, as the flowers 

 upon which they feed in the fields are now nearly all gone. It 

 is at these little fountains on the bark that one finds gathered 

 the quaint family of bumble flower beetles. At other times, I 

 have found them on the bark of willows. A little study shows 

 that their appetite for the sap is intense, and that they know 

 where to find it. Each little sap well has its patronage of 

 beetles gathered around it. Further search revealed two more 

 sap fountains on the tree trunks with many furry beetle attend- 

 ants. In one party of feasters there were thirteen, while at 

 the other, fourteen banqueters were variously disposed. The 

 sexes were about equally divided in the colonies. 



The sharpest eyes are necessary to detect the bumble flower 

 beetle on the bark of trees, for he is securely protected by the 

 blending of his minute yellow and black speckled markings 

 with those of the background. When at rest, his wings are 

 drawn in out of sight. On catching one of the insects in the 

 hand, a peculiar nauseous secretion is given off. This is sup- 

 posed to be useful in self-defence. The secret of his masquer- 

 ading as a bumblebee while flying, lies in the fact that his thorax 

 is clothed with yellowish hairs. Moreover, the ease with which 

 he can spread and operate the smoke-colored wings, which 

 resemble those of the bumblebee also aids in this deception. 

 Unlike most beetles during flight, his wing-covers remain closed; 

 the wings spreading out from beneath the base of these struc- 

 tures. The margins of the wing-covers are roundly excavated 

 near the base, thereby allowing the wings to pass freely out- 

 ward from the sides without the necessity of raising them. 



One can quite easily conceive the advantages to be gained 

 by this insect in even partially mimicking the bee while on the 

 wing. Hovering about the flowers on which he feeds in the 

 same situations as the bee, he probably enjoys protection in 

 taking on the features of his well-armed ally, for the ceaseless, 

 active birds are ever on the lookout for defenceless insects. 

 It would also seem probable that the bumble flower beetle 

 is exempt from these enemies, when it is remembered how easily 

 we could pass him by while he was on the tree trunks, or take 



