The perforation as well as the fertilization of flowers has received attention, but there is a wide field for further study for those who have leisure to pursue it, as it requires much time and patience, as well as closeness and accuracy of observation.

The accompanying figures, from drawings by Mr. C.E.  Faxon, show a few characteristic perforations and mutilations, and also represent two of the principal kinds of insects which make them.

Any one interested in the subject will find an excellent brief review of the work already done, a fair bibliography, and a list of perforated flowers in Professor L.H.  Pammel’s paper on the “Perforation of Flowers,” in the Transactions of the St. Louis Academy of Science, vol. v., pp. 246-277.

The general beauty of flowers is usually not greatly marred by the perforations except in a few cases, as when the spurs of columbines and corollas of trumpet creepers are much torn, which frequently happens.

The great object of the perforations by insects is the obtaining of the concealed nectar in an easy way.  Very naturally, flowers which depend on insect agency for fertilization rarely produce seed when punctured if they are not also entered in the normal way.  Perforating is only practiced by a small number of species of insects, and many but not all of the perforators do so because their tongues are too short to reach the nectar by entering the flower.  Some obtain nectar from the same kind of flower both in the normal way and by perforating.

The chief perforators of flowers, in this part of the continent at least, appear to be some kinds of humble bees (Bombus) and carpenter bees (Xylocopa).  These insects have developed an unerring instinct as to the proper point to perforate the corollas from the outside, in order to readily get at the nectar.  The holes made by the humble bees and by the carpenter bees are usually quite different and easily distinguished.

The humble bees have short, stout, blunt jaws, ill adapted for cutting, and the perforations made by them are apparently always irregular in shape, and have jagged edges.  It has been stated that the humble bees often bore through the tubes of their corollas with their maxillae, but in all cases observed by me the mandibles were first brought into use in effecting an opening.  The noise caused by the tearing is often audible for a distance of several feet.

The true jaws of the carpenter bees are not any more prominent or better adapted for making clean-cut perforations than those of the humble bees; but behind the jaws there is a pair of long, sharp-pointed, knife-like, jointed organs (maxillae) which seem to be exclusively used on all ordinary occasions in making perforations.  The inner edges of these maxillae are nearly straight, and when brought together they form a sharp-pointed, wedge-shaped, plow-like instrument which makes a clean, narrow, longitudinal slit when it is inserted in the flower and shoved forward.  The slits made by it are often not readily seen, because the elasticity of the tissues of some flowers causes them to partially close again.  When not in use the instrument can be folded back, so that it is not conspicuous.  The ordinary observer usually sees no difference between the humble bees and the carpenter bees, but they may be readily distinguished by a little close observation.