[Illustration:  THE PERFORATION OF FLOWERS.

1.  Xylocopa and heads of male and female. 2.  Bombus and head. 3.  Dicentra spectabilis, showing punctures. 4.  Ribes aureum. 5.  Ligustrum Ibota. 6.  AEsculus glabra. 7.  Lonicera involucrata. 8.  Caragana arborescens. 9.  Andromeda Japonica. 10.  Buddleia Japonica. 11.  Mertensia Virginica. 12.  Rhododendron arborescens. 13.  Corydalis bulbosa.]

No doubt, in some of the recorded cases of perforations, carpenter bees have been mistaken for humble bees.  The heads of all our Northern humble bees are rather narrow, retreating from the antennae toward the sides, and with a more or less dense tuft of hair between the antennae.  The abdomen, as well as the thorax, is always quite densely covered with hair, which may be black or yellowish or in bands of either color.  With possibly one or two exceptions, the only species I have seen doing the puncturing is Bombus affinis, Cresson.

The carpenter bees (Xylocopa Virginica) of this region have the head very broad and square in front, and with no noticeable hair between the antennae.  The heads of the male and female differ strikingly.  In the male the eyes are lighter colored and are hardly half as far apart as in the female, and the lower part of the face is yellowish white.  The female has eyes smaller, darker, and very far apart, and the whole face is perfectly black.  The abdomen is broad, of a shining blue-black color, very sparsely covered with black hairs, except on the first large segment nearest the thorax.  On this segment they are more dense and of the same tawny color as those on the thorax.  But it is particularly from the character of the head that the amateur observer of the perforators may soon learn to distinguish between a Xylocopa and a Bombus as they work among the flowers.  It is also interesting to know that the Xylocopas are not so inclined to sting as the humble bees, and the males, of course, being without stinging organs, may be handled with impunity.

Among other insects, honey bees have been said to perforate flowers, but authentic instances are rare of their doing much damage, or even making holes.  I have only recorded a single instance, and in this a honey bee was seen to perforate the fragile spurs of Impatiens.  When searching for nectar they quite commonly use the perforations of other insects.  Wasps and other allied insects also perforate for nectar.  My only observations being a Vespa puncturing Cassandra calyculata, an Andrena (?) perforating the spurs of Aguilegia, and Adynerus foraminatus biting holes close to the base on the upper side of rhododendron flowers.  The holes made by some of the wasp-like insects are often more or less circular and with clean-cut edges.  The ravages committed by larvae, beetles and other insects in devouring flowers, or parts of them, do not properly come under the head of perforations.