History and Habits of Pityogenes. 31 
fore it is not necessary for him to enlarge the nuptial cham- 
ber. Very often the nuptial chamber is not large enough 
to accommodate the male and his several mates at the same 
time. This does not seem necessary for if the females re- 
quire more than one fertilization, as the females of other 
bark beetles are known to do, they can be accommodated indi- 
vidually while the others remain in their egg galleries. 
There can be no doubt whatever that the male of P. hop- 
kinst invariably begins the brood burrow by constructing 
the entrance gallery and nuptial chamber. The construction 
of many entrance burrows has been observed and this work 
was always started by the male. In several cases where 
males abandoned their work after penetrating half of their 
length into the bark, these burrows were found by females 
and carried deeper, but on opening these after several davs 
the character of the burrow was found to be quite different 
from those made by the males. There was no nuptial cham- 
ber present but the entrance burrow had been continued as a 
simple eylindrical excavation, the female apparently using 
it merely as a feeding burrow (Fig. 23, e). 
To determine definitely which sex constructed the nuptial 
chamber, burrows in a culture started March 20th were 
opened five days later. Of twelve thus examined seven con- 
sisted of an entrance gallery and a typical nuptial chamber 
and each contained a single male and no females, one con- 
tained one male and one female and four were inhabited by 
one male and two females in each. This evidence seemed 
fairly conclusive yet in order that there might be no ques- 
tion a new culture was started April 20th and opened two 
days later. The idea being to allow the work to proceed far 
enough to determine whether it was a brood burrow or feed- 
ing burrow and to examine them early enough (before 
the entrance of the other sex) to determine which sex con- 
structed the nuptial chamber. Seventeen burrows were ex- 
amined. ‘Ten of these each contained a single male and of 
these ten seven showed typical nuptial chambers while three 
had not proceeded far enough for the character of the bur- 
row to be certain. Five burrows were occupied by one male 
