190 EXPERIMENTAL FARMS 



5-6 EDWARD VII., A. 1906 



The Spruce Gall-louse (Chermes abietis, L.)- — An insect wliicK is spreading 

 widely through the Dominion and which of late years has been the cause of much 

 anxiety among the growers of ornamental spruces and even of lumbermen, is the Spruce 

 Gall-louse. This is the insect which causes the elongated green cone-like galls on the 

 twigs of the native Black and White Spruces and of the imported Norway Spruce. 

 These galls have been more than usually abundant during the summer of 1905, par- 

 ticularly upon young transplanted trees. Specimens have been sent in from many 

 places. 



Although undoubtedly the Spruce Gall-louse does injure trees to a serious extent 

 when present in large numbers and also gives them a very unhealthy and unsightly 

 appearance, still I do not know of any actual instances where it has killed trees out- 

 right. 



About the end of July the galls begin to dry up, and the cavities at the base of the 

 ieaves open slightly and allow the young gall-lice, of which there are several in each 

 cavity, to escape. These then crawl out and rest upon the leaves, and after a short 

 time they moult and appear with wings. This is the time when the insect spreads from 

 tree to tree; for these mature females fly to fresh trees or to fresh branches on the 

 same tree and begin to lay small, pale yellow eggs, which are in clusters of from 20 to 

 50 together. From these eggs young plant-lice hatch, which remain on the twigs and 

 at the base of shoot buds until the following spring. Many of these young lice, how- 

 ever, die before spring, and those which do survive the winter, may be found at the 

 bases of the buds in May, enveloped in a coat of white waxy threads. These young 

 plant-lice are very small when winter sets in; but in spring they grow rapidly, and, 

 after moulting the old winter coat, they secrete another of much finer texture and much 

 more conspicuous, of long woolly threads. When full grown these insects, which are 

 all females, lay clusters of upwards of 300 eggs at the bases of the young shoots just 

 about the time the spruces are beginning their new spring growth. The eggs are light 

 yellow in colour, extremely small, about one-sixtieth of an inch in length, and each one 

 is attached by a slender thread-like stem about twice the length of the egg. In about 

 a week the very minute nymphs crawl out from beneath the woolly mass consisting of 

 the dead body of their mother, and crawl on to tlie young shoots, where they take up 

 their position at the bases of the leaves which have already begun to swell and form 

 galls before their arrival, owing to the presence of their mothers during the winter. 

 The green cone-like gall grows rapidly during June ; the base of each leaf swelling and 

 expanding so as to form a cavity which gradually develops and covers in some of the 

 young insects. In time this cavity is closed all but a narrow semi-circular slit at the 

 top. It is claimed by Prof. R. A. Cooley, who did very careful work on this insect 

 while at the Massachusetts Agricultural College, that, in general, all of the nymphs 

 which enter one gall, arise from the egg cluster laid by one female. As the gall grows 

 in size, these cavities are enlarged, this leaves room for the increased growth of the 

 insects which it contains. 



As stated above, these insects do not become full grown and emerge from the galls 

 until the end of July or during August. The remedies for the Spruce Gall-louse, un- 

 fortunately, cannot be applied when the insects occur on very large trees and in for- 

 ests ; but, upon hedges and in ornamental grounds good work has been done by spray- 

 ing the trees at the time the young plant-lice are exposed on the trees, viz., in May, 

 and after they emerge from the galls in August. Good results were secured by spray- 

 ing with a tobacco and soap wash made by soaking ten pounds of tobacco leaves in 3 

 or 4 gallons of hot water for six hours, the liquid strained off and two pounds of whale- 

 oil soap added. When the soap is all dissolved, the mixture can be diluted to 40 gal- 

 lons. Two or three applications should be made at short intervals. 



The Larch Sawflt (Nematus erichsonii, Hartig). — About 20 years ago the Larch 

 Sawfly was imported into America, probably with trees sent to the Harvard Arboretum 

 and Botanic Garden at Cambridge, Massachusetts. From that point it seems to have 



