1911 ENTOMOLOGICAL SOCIETY. 83 



are cut in the bark along the sides, and in these the eggs arc deposited, on end, and 

 packed in dust. Usually three eggs are found in a pocket, but sometimes 4, 2 or 1. 

 The pockets are cut at the end of the tunnel on the side, so that the female must 

 reverse her position to oviposit. The diameter of the tunnel will not admit of 

 this, so along the sides of the tunnels are found wide niches, as wide as the tunnel, 

 which may be called turning-niches. These seem to he used by the beetles in 

 turning about and in passing each other in the tunnel. Very rarely an egg or two 

 will be laid on their sides. Tlie eggs of one pocket being laid, the female lengthens 

 the tunnel and cuts another egg-pocket, and so on until all her eggs are deposited. 

 The chips resulting from the boring operations, together with the excrement 

 of the beetles, are packed firmly backwards towards the entrance hole, and not un- 

 commonly eggs are found packed in this mass. By the time the tunnel has neared 

 completion, we find usually a female in a clear space at the tunnel's end, and 

 behind her the dust packed firmly with one or two clear spaces at intervals, in 

 each of which will be a male completely walled in and contentedly feeding on the 

 chips or on the sides of the tunnel. Not infrequently there will be an egg-tunnel 

 branching from the first, cut by a female which had entered the first tunnel before 

 the entrance was blocked with chips. These side tunnels often open into neighbor- 

 ing egg-tunnels, so that adjoining tunnels appear to anastomose. Occasionally 

 ventilation holes are cut in the bark forming the tunnel roof, but very few of these 

 were noticed. 



The larvae which hatch from the eggs along the tunnel sides bore into the bark 

 away from the egg-tunnel, cutting the larval galleries, which at first very tiny 

 and entirely in the bark, gradually increase in diameter as the larvae grow, and 

 finally score the wood. The larval galleries are extremely irregular, crossing and 

 recrossing each other until the bark of that part is almost entirely reduced to 

 powder, which packs the galleries. The larvae which hatch from eggs laid in the 

 chips packing the egg tunnel feed upon the mass of chips for a time, and later 

 enter the bark from the tunnel sides. 



Egg-laying lasts over a considerable period. Eggs and newly hatched larvae 

 of the second brood were found as late as August 26th. This second brood matured 

 in sticks in the laboratory early in October, and emerged through holes in the bark. 

 Polygraphus rufipennis. This common bark beetle of spruce and pine seems 

 quite as ready to attack dying larch bark, for we found it this season in great num- 

 bers in the piled larch trunks and tops and the felled larches lying in the clearing. 

 I have never found this species in healthy trees. It is very common in dying bark 

 of spruce, and, in our section, in red and white pine. This is a small bark beetle, 

 3mm. long, of a uniform dark brown or nearly black colour. It is readily dis- 

 tinguished by the combination of divided eyes and undivided, distally pointed, 

 pubescent antennal cl,ub. Its work is well illustrated in the collection exhibited. 

 An entrance hole is cut through the bark and a shallow chamber, called the nuptial 

 chamber is excavated therein. From this chamber are cut in a radiating fashion, 

 and between the bark and wood, from three to five egg-tunnels. The females cut 

 the tunnels and in the nuptial chamber will be found the only male busy ejecting 

 through the entrance hole the boring dust which the females have brought to the 

 tunnel entrances. The eggs are laid singly along the sides of the tunnels, each 

 in a tiny pocket called an egg-niche, and firmly packed in dust; so that the sides 

 of the tunnel are smooth and the eggs completely hidden. From a few to twenty 

 eggs will be found on each tnnnel side. The larvae which hatch from the eggs bore 

 [ into the bark directly away from the egg- tunnels. When the larvae are not much 

 I crowded their tunnels are fairly regular, but when many egg-tunnels lie close 



