192 BULLETIN 407 



larva, for suddenly it bursts at the anterior end, and as the larval head 

 is pushed thru, the opening is gradually enlarged until a slit extends more 

 then one-half the length of the egg. No egg burster of any kind was 

 found on the larva. 



The larva 



Activities of the newly hatched larva 



The newly hatched larva has the appearance of most Cerambycid 

 larvae. It measures 1.8 millimeter in length, while the prothorax, which 

 is the broadest part of the larva, measures .9 millimeters in width. The 

 mouth parts are black, while the head, behind the mouth parts, is brownish 

 in color. The different segments are sparsely covered with delicate, 

 long hair. 



Immediately after hatching, the tiny larvae migrate in under the scales 

 of the bark, where the eggs have been deposited, as far as the size of the 

 prothorax will allow, and then, using the scale of bark as a brace, begin 

 to burrow in towards the wood. It takes about twelve hours to burrow 

 deep enough so that they are completely concealed and during this time 

 fine, powdery sawdust is pushed out behind them. Under natural 

 conditions, where the eggs are laid in clusters of only four or five, there 

 is but little mortality among the young larvae, each individual being 

 able to establish a burrow by itself. But when a large number of eggs are 

 laid in a single crevice, as was done by the specimens kept at the insectary, 

 there is not room enough for all of them to get started. Accordingly, 

 two or more penetrating into a single burrow, one is punctured by the 

 mouth-parts of the other and is killed. Out of fifty-two larvae hatching 

 in a single piece of hickory, only twelve were able to survive and establish 

 burrows. Moreover, when the bark is smooth and no crevices or scales 

 are present to serve as braces for them in beginning their burrows, they 

 are unable to penetrate the bark and soon die. In like manner, the larvae 

 are unable to burrow into material from which the bark has been 

 removed. 



Larval burrows 



Having penetrated the bark, the young larvae drive their long, linear 

 burrows with the grain of the wood, grooving the inner bark as well as 

 the sapwood. Each burrow usually begins as a small gallery -^ inch 

 wide and of about the same depth. Gradually increasing in width and 

 depth, it may extend for a distance of from 8 to 12 inches or even more, 

 after which it usually bends on itself to form a long, narrow, irregular U, 

 whose arms may be either in contact with each other or slightly separated ; 

 on the other hand, the gallery may consist of several loops which are either 



