REPORT OF THE ENTOMOLOGIST. 



381 



anil examining it, September G-8, t lie eggs had in some cases batched 

 and the larva 1 had began to descend slightly into the bark, On hatch- 

 ing they begin at once to gnaw a mine, throwing (heir castings out 

 through the gash originally made by the female, so that it was ensy to 

 ascertain without disturbing the bark whether the eggs had hatched or 

 not. The rarVSB indifferently lie with either side, dorsal or ventral, pre- 

 sented outwards. Three days alter (September 12) several had bored 

 through the pieces of bark, making the usual flattened oval hole, but 

 probably in nature the larva remains hidden in the bark through the 

 winter, not beginning to penetrate the wood until the following spring. 



The length of the larva when freshly hatched was 5-G mni , and the 

 body was rather stouter than in the fully-grown larva. (Plate V, Fig. 

 3, b.) 



How many eggs are laid by the female is not known, but, probably, 

 judging by their large size, comparatively few. 



Another female was found on the same tree. Over a hundred gashes 

 had been made on the western side of this fir tree over a space 4 feet 

 long; the gashes were so fresh that they must have been made on that 

 and the previous days. They were quite conspicuous, and could, after 

 one had become familiar with their appearance, be detected at the dis- 

 tance of 5 or feet from the tree. I suspect that the sexes couple fre- 

 quently during the operation of egg-laying, as the male was standing 

 so near his mate with his antennae outstretched and intently watching 

 the female while at work. The males are also probably polygamous. 



The industry of the female is well shown by the number of gashes 

 made (Plate VI, Fig. 1, a, b), some |of which did not, however, contain 

 any eggs. In the space of a square inch there were three gashes, 

 while in the region where they were thickest forty were counted in half 

 a square foot. Of course when they hatch all do not live to pass through 

 their transformation. Whether the woodpeckers seek for and discover 

 the larvas ensconced in the bark is doubtful, and yet it would be easy for 

 them or other birds to pick the grubs out of their hiding-places. So far 

 as my observations have gone the holes made by the woodpeckers in 

 forest trees are for the purpose of getting at the inner bark rather than 

 for insects. But a careful examination of woodpeckers shot in conifer- 

 ous forests would throw light on this subject. 



In regions where the white pine grows it is infested by the Mono- 

 hauimus. The spruce is also often infested, but I have not seen clear 

 cases where either of those trees have been killed outright by this de- 

 structive borer. But during the past summer I have seen on the isl- 

 ands in Casco Bay and taken out the full grown larvae from at least six 

 or seven living firs, which must have been killed by the attack of this 

 borer, which has been the evident cause of the death of many firs in 

 Elaine. 



I have seen hundreds, perhaps nearly a thousand, dead firs whose 

 trunks were riddled with the holes of these borers. The spruce is less 

 frequently killed, but I have taken from a dead tree two pieces of spruce 

 bark, each about 6 inches square, one containing sixteen and the other 

 eighteen holes through which the beetle had escaped. PI. VII, Fig. 1, 

 represents one of these specimens of natural size. 



