1911 ENTOMOLOGICAL SOCIETY. 81 



greenliouses, without, however, destroying or endangering the health or life of 

 plants or of the operator of this remedy, and I would encourage in every way pos- 

 sible the use of this means that these insects, if not totally destroyed, are still so 

 kept in check as to do but the minimum of harm. 



SOME INSECTS OF THE LAECH. 

 J. M. SwAiNE, Macdonald College, Que. 



It is my intention to describe to you this afternoon rather briefly an attack 

 made this summer upon a small clump of larch by a series of scolytid beetles; and 

 to use this attack as an illustration of the breeding habits of Scolytidae in our 

 great forests of pine and spruce. 



The larch bush to which I refer is situated at Hudson, about ten miles west 

 of Ste. Anne's. The trees were fine specimens of Larix of medium size, with an 

 average height of perhaps 40 feet, and until this season had been particularly 

 healthy. Previous to this season I had not taken a scolytid from larch in that im- 

 mediate neighborhood. Last winter a wide section was cut through the bush, and a 

 plank walk laid through it, about three feet from the ground. The stumps were 

 left rather high; the greater part of the rubbish was removed; several untrimmed 

 larches were left lying in the clearing and one was lying well shaded by standing 

 rrees; and the trunks which had not been removed were piled in the clearing and 

 lefl to dry through the summer. 



The scolytids which attacked the dying bark, thus provided, belonged to five 

 species : Dendroctonus simplex, Dryocoetes autographus, Dryocoetes n. sp., Ips 

 caelatus and Ips halsameus. In the wood of the stumps an ambrosia beetle, 

 Gnathotriclius materiarins, bred in large numbers. 



I wish first to discuss the habits of these species very briefly. 



D. simplex, Lee. This species is the common Dendroctonus of larch and is 

 probably to be found wherever that tree is abundant. It is recorded from West 

 Virginia northwards to Ungava and west to Michigan, and I have seen specimens 

 in Mr. P] vans' collection from Macldnak, Man. As the larch is found throughout 

 all Eastern Canada excepting Northern Ungava and westwards to the Rockies, ex- 

 cepting the Barren Grounds, this beetle will probably be found throughout all that 

 region. It is not a particularly injurious species. It prefers the bark of stumps 

 and recently cut and dying trees, but will attack apparently healthy trees when 

 dying bark is not to be obtained. It occurs chiefly in the bark of the trunk. 



This species was first noticed this season on July 10th in the bark of larch 

 stumps. The trees had been cut the preceding winter, and cleared away, leaving 

 stumps about II/2 feet high. The place was swampy, and although the stumps 

 were in the open sunlight, they remained sappy throughout the season. Only a 

 part, perhaps half, the stumps of the clearing were attacked by this species. On 

 July 10th — the date on which they were first noticed — the egg-tunnels contained 

 eggs in the outer ends; and larv^ of all sizes, from those recently hatched up to 

 nearly full-grown, were boring in the bark. There were no pupte and no young 

 adults. 



About a month later (August 6th) the tunnels in these stumps contained full- 

 grown larvae, pupae, recently transformed, light coloured adults, and older, darker 

 adults; and many adults had escaped, as evidenced by the holes through the bark 

 above the ends of the larval tunnels. The larvas were in tunnels coming from the 



