18 BULLETIN 1107, U. S. DEPARTMENT OF AGRICULTURE. 



between two sections of wood, or where a section of wood rests against 

 something else, in fact any place where the proper leverage can be 

 obtained, she starts boring. 



Gnawing, and circling as she gnaws, she soon has in the bark or 

 wood a circular impression with a smooth rounding edge and slightly 

 larger than herself. During this time her claws grasp the bark or 

 wood and her abdomen is parallel with the surface. As soon as the 

 hole is deep enough she gets the prothorax with its rasplike rugosites 

 against one side and with the front pair of legs grasps the other side. 

 The legs of the middle pair brace and push with the tibial spurs, 

 while those of the rear pair extend backward close to the abdomen, 

 which gradually becomes elevated as the boring progresses. Con- 

 tinually gnawing and revolving back and forth, sometimes making 

 a complete circle, she eventually buries herself in the wood perpen- 

 dicular to the surface. This takes about 24 hours. 



Apparently the boring goes on continuously, faster during the 

 warmer part of the day and slower during the cooler night time. 

 The borings are kicked out by the legs. As the gallery deepens the 

 insect has to back up, kicking out the borings as she comes. The 

 male often assists the female by pushing against her declivity with 

 his mandibles, thus adding weight and stability to the hold. He also 

 assists in throwing out borings when the gallery gets deeper. 



"When the gallery has reached a depth of about 8 millimeters, 

 which is slightly more than the length of the female, it turns rather 

 abruptly, curves backward toward the surface, and then runs par- 

 allel to it across the grain of the wood. (PI. Ill, Fig. 1.) The 

 length varies from a few millimeters to 125 millimeters, or about 5 

 inches. The average length is about 63 millimeters, or 2|- inches. 



Mating. — Mating usually takes place about the time the female 

 has bored her length into the wood. Sometimes in the laboratory 

 pairs were found mating on windows, etc., but most of the observa- 

 tions indicate that this is abnormal. Usually the mating is started 

 by the male clawing at the declivity of the female with his front feet. 

 Sometimes, however, he backs up to her and uses his back feet. 

 Upon being clawed, the female protrudes her anal segments with the 

 sexual organ, whereupon the male places the tip of his abdomen to 

 hers and they mate. (PI. Ill, Fig. 3.) Copulation lasts from 10 to 

 70 seconds. Our records show that one copulation is sufficient. 

 One female laid at least 140 fertile eggs after being separated from 

 the male. (See diagram, Fig. 13.) 



Egg laying. — As the egg laying occurs in the wood it was not 

 observed, but the observations made on the egg galleries and the eggs 

 shortly after they were laid indicate how it was done. Any time 

 after the female has reached the solid wood she places the ovipositor 



