62 College of Forestry. 
With the entrance of one or more females into the bur- 
row the male ceases burrowing and spends most of his time 
at the entrance in the guarding position. It is his duty also 
to dispose of the frass derived from the egg galleries which 
the females leave in the nuptial chamber. 
Copulation occurs in the burrows, the female lying in her 
egg gallery with the end of her abdomen at the juncture of 
this with the nuptial chamber, while the male hes in the 
nuptial chamber. It was not detérmined whether each 
female was fertilized more than once or not, but that fre- 
quent copulation is not necessary is proved by the fact that 
the female will continue egg laying for as many as eight 
days after the male has been removed from the burrow. 
Egg laying begins within a few hours after copulation and 
continues for a period varying from several days to two 
weeks. Eggs are laid at the rate of from two to eight per 
day, the average number for a vigorous female being about 
four to six per day. 
The incubation period varies with the temperature but the 
average is about seven days. 
Movements of the embryo larvae may be observed through 
the egg membranes twenty-four hours or more before hatch- 
ing. These consist not only of a movement of the entire 
larvae but also a continuous opening and closing of the brown 
mandibles. 
The larva eats through the egg membranes on the side 
next to the bark and after devouring part of these mem- 
branes, begins its burrow. ‘The first part of the burrow is 
entirely in the bark but upon the surface of the wood, while 
the later burrow grooves the sapwood deeper and deeper 
until the nearly full-grown larva excavates from one-half to 
more of the burrow from the wood. 
The newly hatched larva is widest through the head but 
soon after it begins feeding, the rest of the body grows rapidly 
in all three dimensions while the head does not increase in 
width till the first moult. 
Careful measurements of the heads of numerous larvae 
shows that the larval period comprises five instars and a care- 
