HYMENOPTERA. 423 



one of which represents the two backs of the saws of tlie saw- 

 flies, joined together, and encloses two needles for boring holes. 

 The part, serving for a back to these needles, is notched on 

 each side, and the needles themselves, which are as fine as a 

 hair, and as strong and elastic as wire, have several small 

 teeth along the lower side towards the end. These needles, 

 and the back in which they play, are so connected as to ap- 

 pear to be only a single spear-pointed awl. With this com- 

 plicated and pow^crful tool the females bore holes into the 

 trunks of trees, wherein they drop their eggs. Their young 

 are cylindrical and fleshy grubs, of a whitish color, with a 

 small, rounded, horny head, and a pointed and horny tail. 

 They have six very small legs under the fore part of the body, 

 and are provided with strong and pow^erful jaws, wherewith 

 they bore long holes in the trunks of the trees that they in- 

 habit. Like other borers, these grubs are wood-eaters, and 

 often do great damage to pines and firs, wherein they are most 

 commonly found. When fully grown, the grubs make thin 

 cocoons of silk, interwoven with little chips, in their burrows, 

 and in them go through their transformations. The chrysalis 

 is somewhat like the winged insect in form, but is of a yellow- 

 ish white color, till near the time of its last change, and the 

 w^ings and legs are folded under the breast; in all these respects 

 it agrees with the chrysalids of other Hymenopterous insects. 

 After the chrysalis skin is cast off, the winged insect breaks 

 through its cocoon, creeps to the mouth of its burrow, and 

 gnaws through the covering of bark over it, so as to come out 

 of the tree into the open air. It is stated that the grubs of 

 the large species come to their growth in seven weeks after the 

 eggs are laid. K this be true, and it seems hardly possible, 

 the chrysalis state must last a long time, for the perfected 

 insects have been known to come out of timber that had been 

 cut up and applied to mechanical uses by the carpenter. Some 

 persons have supposed that they attacked only diseased and 

 decayed trees, in which it must be admitted they are often 

 found in great numbers. But many instances might be men- 

 tioned of their appetite for sound wood also, and it is probable 

 that the presence of these insects, like that of many others, is 



