92 Psyche [August 



less is used by the female for reversing her position in the burrow. 

 The remainder of the egg-gallery is a simple cylindrical mine which 

 extends longitudinally, typically nearly straight, but frequently 

 more or less curved. Its diameter is just great enough to allow 

 convenient passage of the beetle. In length these egg-galleries 

 vary from 50 to 85 mm. with an average of about 70 mm. 



A number of instances have been observed where the same en- 

 trance gallery has been used in common by two or more pairs of 

 beetles. That these are not cases of true polygamy is evidenced 

 by the fact that each egg gallery arising from the common entrance 

 has its own nuptial recess, and also by the fatjt that in all instances 

 where the beetles were still present, the two sexes in these multiple 

 burrows occurred in equal numbers. 



The eggs are laid by the females either in niches or in longitudi- 

 nal grooves along one or both sides of the egg-galleries, more typi- 

 cally in grooves. Most of the females appear to use the grooves 

 entirely, a considerable number use both niches and grooves and 

 none have been observed to use the niches exclusively. In the 

 side grooves, the eggs are deposited in considerable numbers, often 

 forming a layer several tiers wide, but when niches are used only 

 from two to six are placed in one recess. In all cases the eggs are 

 securely packed and the niche or groove closed with a layer of saw- 

 dust so that the opening of the gallery is of nearly uniform bore 

 and the beetles may pass through it without endangering the eggs. 

 No attempt has been made to count the eggs or larvae of a single 

 pair, but the number must be considerable as often the combined 

 length of all of the egg-grooves of the two sides is equal to or greater 

 than the length of the egg-gallery. In fact, the brood of Hylurgops 

 is so numerous and their appetite so voracious, that it is very 

 difficult to obtain brood-burrows fit for study unless the bark is 

 stripped off before the larvae have fed many days. Otherwise 

 the feeding galleries of the larger larvae and the young adults are 

 carried back and forth over the egg-galleries until these become 

 entirely unrecognizable. 



The ability of the larvae to live under adverse conditions is well 

 illustrated by the following observations: On June 18, 1915, near 

 Cranberry Lake, N. Y., several stumps of large white pine trees 

 felled during the preceding winter were found to be heavily infested 

 with Hylurgops pinifex, Dendrodomis valens Hopk., Ips pini Say, 



