527 



blisters. This sawfly appears in late May or early June and oviposits 

 through slits in the upper surface of the leaf. The eggs hatch in about 

 8 days and the young larvae begin to construct individual mines in 

 the leaves ; these later become joined up with other mines until the 

 entire parenchyma of the leaf is eaten out and the upper surface is 

 brown and badly blistered. After feeding for about three weeks 

 the mature larva drops to the ground, enters the soil to the depth of 

 about one inch and there constructs a cocoon in which it pupates, 

 the adult emerging about 3 weeks later. There are two generations 

 in a year, with sometimes a partial third, the broods overlapping. 



Natural control seems to be exercised to a certain extent by a species 

 of mite and by a Hymenopterous parasite. Many of the adults have 

 been observed caught in spider webs, while many appear to become 

 imprisoned in their cocoons and never reach the surface of the ground. 

 Artificial control has been tried by means of several contact insecticides, 

 the best of which was 1 part kerosene emulsion to o parts v;ater, which 

 killed practically all the larvae if applied when they were young ; 

 when they have just hatched, 1 part kerosene emulsion to 7 of water 

 is effective. Certain species of alder seem to be immune to attack 

 by K. dohrni, probably owing to the thick and hard texture of the 

 leaves. 



SwAiNE (J. M.). Some Insect Injuries in Woodlots. — lltli Ann. Rept. 

 Quebec Soc. Prot. Plants Jrom Insects and Fungous Diseases, 1918- 

 1919 ; Quebec, 1919, pp. 46-48. 6 figs. [Received 14th October 

 1919.] 



Insect injuries to balsam and spruce in Quebec are described, 

 ])articularly in regard to the insects infesting farm wood-lots. These 

 have undoubtedly arisen largely in consequence of the great outbreak 

 of the spruce bud-worm [Tortrix fumiferana] that occurred in the 

 western half of the Province several years ago [see this Review, Ser. A, 

 vii, p. 299]. Particular injuries dealt with are those caused by the 

 eastern balsam bark-beetle, PiiyoUeines spars us, Lee, erroneously 

 referred to in a previous notice [loc. cit.] as Ips bcdsameus, Lee, and 

 by the eastern balsam bark- weevil, Pissodes dubius. Rand. The eggs 

 of the latter are laid in early summer in small punctures cut in the 

 bark of the trunk of healthy or weakened balsams. The egg-punctures 

 are arranged in groups and form conspicuous patches owing to the 

 dried balsam that exudes from the tree. The larvae excavate long 

 winding mines between the bark and wood. The young beetles, 

 after maturing in the end of the larval mines, emerge through the bark 

 early in the following season. The injury to young balsam has been 

 extensive and spruce is suffering in a less degree from similar causes. 



The bronze birch borer [Agrilus anxius] caused the death of many 

 white and yellow birches in the summer of 1918. The infested trees- 

 die gradually from the top downwards. By the time the top of the 

 tree is dead, the grubs are constructing their tunnels in the apparently 

 healthy bark below, and cutting of! the tree top generally only checks 

 the attack temporarily. All trees found infested should be cut and 

 utilised the same winter. Destruction of infested trees before June 

 will check the spread of the beetles. 



