1906 • ENTOMOLOGICAL SOCIETY. 105 



IN THE TRACKS OF NEMATUS EEICHSONII, HARTIG. 

 By Rev. Thomas W. Fyles. D.C.L., F.L.S. 



It is- a law of nature that no particular growth of plants should hold 

 possession of the land in perpetuity. Sooner or later destructive agents will 

 break in upon the scene.. Insect depredators, drought, fire, storm and, flood 

 — these, and the axes of the lumbermen, make clearances for occupation by 

 the settler, or for Nature's re-planting. In the latter case we find that the 

 new growth is, generally speaking, different from the old. The following 

 affords a curious exemplification of this fact : — 



In 1842, when the Ashburton Treaty was made, a strip, 60 feet wide, 

 was cut along the border, through the tamarack swamps that extend from 

 Canada into New Hampshire and Maine. This strip is now filled up with 

 a new growth; but the forester knows directly when he strikes the line, for 

 he finds a belt in which the poplar (Populus trcTnuloides) , the red cherry 

 {Prunus Pennsylvanica), and the Moosemissie (Pyrus Americana), are grow- 

 ing, the seeds of the first having been carried by the wind into the Bound- 

 ary, when newly cleared; and those of the last two, by birds. 



Thirty years ago it was a fine sight to look, from an elevation, upon the 

 vast area of swamp land, extending through Bury, Lingwick, Hampden, 

 Ditton, and far away. Tamaracks from two feet to two and a half feet in 

 diameter, were the lords of this forest-land. To-day, I have the authority 

 of Mr. Ayton Cromwell and Mr. C. C. Lusk, of Cookshire, and Mr. C. H. 

 Ward, of Bury — all experienced foresters — for stating that not a single 

 first-growth tamarack is to be found in the whole section. And like testi- 

 mony comes to me from Mr. John D. Johnson, of St. Thomas, and Mr. E. 

 W. Brewster, of Compton, in regard to the districts with which they are 

 respectively acquainted. 



How was the destruction brought about? By an agent seemingly in- 

 significant and wholly unexpected — a four-winged fly, belonging to the 

 order Hymenoptera, and named by Hartig,' Nematus Erichsonii. 



This fly is only about eight-tenths of an inch in expanse of wings, and 

 four-tenths in length of body. Its colour is black, but it has a broad orange- 

 red band round the abdomen. Its wings are clear, with dark veins, and a 

 conspicuous costal spot or stigma. 



In the larval stage — which is the destructive stage — the species is a 

 green caterpillar of no great size, having a black head. When it is' "full- 

 fed," it creeps into some retreat, and spins a compact, brown cocoon, about 

 half an inch in length. 



It was in the pupal stage, probably, and amongst the roots of young 

 plants of Norway Spruce, that the species was brought to the nurseries of 

 Massachusetts, about the year 1880. 



The first notice of the arrival of the Nematus in Canada was given by 

 myself, and will be found on the 17th page of the Report of the Entomolo- 

 gical Society of Ontario for 1883. When the creatures came to us, they 

 came in their strength — "In numbers numberless." The Nematus Raid, as 

 it was called, was a phenomenon that they who witnessed are not likely to 

 forget. That creatures seemingly so insignificant, brought unwittingly from 

 a country so far away, should, by force of numbers, be able to strip the 

 vast forest of tamarack of its verdure, and leave the trees in a dying state 

 was truly marvellous. 



I last saw the creatures in activity about ten years ago, in a grove of 

 young tamarack near the old St. Henry Road, in Levis County. The trees 

 were about twenty feet high ; and here and there amongst them was a small 



8 EN. 



