Insects Bred from American Larch 53 
Deer Of engravings studied. , 2. ......¢..ecceeecseens 156 
Number of engravings having one-egg gallery............ 25 
Number of engravings having two-egg galleries.......... 111 
Number of engravings having three-egg galleries......... 20 
Total number of Epa SaMleNIEs ss 6 snentsin AW SSN See eee 307 
Minimum length of ege galleries...............-24-.+<« 2 mm. 
Maximum length of egg galleries...................14-- 90 mm. 
fayerioenlenmtih of ego galleries. . s+. -.c02 «f-an nese scner 27.36 mm. 
Average length of egg gallery in uniramous burrow...... 34.00 mm. 
Average length of egg gallery in biramous burrow....... 27.97 mm. 
Average length of egg gallery in triramous burrow...... 22.35 mm. 
Minimum number of egg niches in one egg gallery....... 2 
Maximum number of egg niches in one egg gallery....... 126 
Average number of egg niches in one egg gallery......... 30.65 
Average number of egg niches in egg gallery of unira- 
MENCONL MM DATS G UW fers cegctcl hoes at Shas col sy iiss nse sevaitch united snes sides th dies aud ad 40.36 
Average number of egg niches in egg gallery of biramous 
Seem rie Taal Se «eis tebwais lh des ss eee Ona aw oleae 31.54 
Average number of egg niches in egg gallery of triramous 
EMP Rens cS hte Sach oe x dls) Wash eie cia oT Se weaned t 23.46 
Average number of egg niches in entire uniramous engrav- 
Oy Spl Ra ee IR Ral AIST ay Ae ie a AE 40.36 
Average number of egg niches in entire biramous engrav- 
MMT SSID ery aie aha tw a wie RM S/e wih gldbve oa Alas 63.08 
Average number of egg niches in entire triramous engrav- 
OTE he Sern calico tle ee tao cb amas SAREE mde 5 as 70.38 
Thus it would appear that just as in P. rufipennis each 
female of H. picew produces a greater number of eggs when 
she shares her mate with no other female. Here also, how- 
ever, the greatest individual reproductive efficiency is shown 
in burrows: occupied by one male and two females and the 
least when more than two females are present. This is 
shown by the following data: 
Number Occupants of burrows Eggs produced 
of egg niches Male Females per individual 
40.36 a (1 at 1) = 20.18 
63.08 == (1 +. 2) a 21.03 
70.38 sis (1 aa 3) = 17.59 
The larval burrows start out at right angles to the egg- 
gallery. At first they are parallel to each other but soon 
become winding in their course, often crossing and recross- 
ing each other. They are rather longer than is usual for the 
