PITH-BORING BEES. 197 



of one of the pith-boring bees, many species of which inhabit this 

 country. This is the insect termed Hykeus dilatatus, and in or- 

 der to assist the reader in identifying it, a figure of the insect it- 

 self is given on the right hand of the nest. Usually, the Hylaeus 

 is obliged to bore its way through the pith by sheer labor, but it 

 will always avoid such a task if possible, and make its cells in a 

 hollow already existing. Such has been the case with the nest 

 from which the illustration was drawn, which was made in the 

 hollow stalk of a hemlock. Here let me mention that all hollow 

 stalks and twigs are likely localities for the nests of insects, and 

 that toward the autumn a rich collection may often be made by 

 the simple process of examining all such objects, and splitting 

 them carefully with a knife. Even the reeds and rushes of the 

 river are apt to contain nests, some of them being exceedingly rare. 



The particular species of Hylaeus which is here figured is by no 

 means common, appearing to be a very local insect, confined to 

 certain spots, and seldom seen except in those favored localities. 

 Very many species of pith-boring insects are known, most of them 

 inhabiting the dry twigs of the bramble and garden rose. If at 

 the cut end of a branch a round hole be found in the pith, the 

 observer may be sure that a nest of some kind is within. Gener- 

 ally, on carefully laying the branch open, there appears a whole 

 series of cells, one above the other, and in such a case, the cells 

 which are farthest from the aperture always contain the larvas of 

 female insects, those nearest the entrance being the males. 



Sometimes the nests which are found in the bramble contain 

 the larvae of Osmia leucomelana, a pretty little bee, scarcely more 

 than a quarter of an inch in length, black in color, with a very 

 glossy abdomen, and a white, downy look about the legs. Five 

 or six cells are made in each branch, and the perfect insect ap- 

 pears about the month of June. 



Other bees of this genus are extremely clever in saving them- ' 

 selves labor. Although they can dig industriously when obliged 

 to do so, they will never exert this power without compulsion. 

 The smaller species are very fond of making their cells inside 

 straws, and a thatched roof often contains thousands of nests, 

 which are unsuspected by man, and only discovered by the tom- 

 tits and other birds, whose sharp eyes soon detect the hidden in- 

 sect, and whose ready bills pull the straws out of the thatch, and 

 pick the larvae from their cells. Nail-holes in garden walls are 

 often filled with cells, and so are the auger-holes in old rails and 

 posts, from which the wooden pins have fallen. 



