REPORT OF THE SOCIETY 35 



THE IMPORTED ALDER LEAF MINER 



C. B. Hutchings, Entomological Branch, Ottawa 



The fine group of alders at the Experimental Farm, Ottawa, has for many- 

 years been attacked by the alder leaf miner, Kaliosysphinga dohrnii Tischbein. 



The most casual observer visiting this section of the Arboretum during the 

 summer months could not fail to notice on the leaves the brown blisters which give 

 the trees the appearance of having been badly scorched. 



This injury is due to a small black saw-fly which appears in early summer and 

 lays its eggs on the leaves. In about a week the eggs hatch and the leaves begin 

 to show signs of the tiny larvae starting their operations. At first, each miner 

 works independently; but it very often happens that many eggs are laid on the 

 same leaf, and the workers meeting with tunnels of other workers, their mines 

 coalesce and in this way the whole upper surface of the leaf is lifted. The larvae 

 attain full growth in three weeks. They drop to the earth then, where trans- 

 formation is carried on within small earthen cocoons just below the surface of the 

 ground. There are at least two broods at Ottawa, and in favourable seasons 

 possibly three, but since the broods overlap it is often difficult to state accurately 

 where one stops and another begins. 



From the few publications available on this subject, it appears that the fly was 

 imported into Canada from Europe, between 30 and 40 years ago, but there is no 

 record of the exact date when this actually occurred. Dr. Fletcher in a report in 

 1891, published in Can. Ent. Vol. 23, p. 252, very briefly referred to it as damaging 

 alders at the Farm. Two years later, 1893, Mr. Harrington of Ottawa noted in 

 Can. Ent., Vol. 25, p. 59, the insect working on native alders near the Farm. 

 That same year Mr. Dyar of N.Y., reported in Can. Ent., Vol. 25, that this insect 

 was seriously affecting the American alders at Wood's Hall, Mass. At Ithaca, 

 N.Y., the fly appeared in 1891, and Mr. Slingerland made a study of it, publishing 

 his results in Cornell Bull. 233. 



Adult: The adult is a small, black saw-fly, 3 mm. long, with very shiny 

 head and body, and wings somewhat smoky. It is very closely related to the 

 Elm Saw-fly and except for a slight difference in the wing venation the two species 

 are very much alike. 



Flights occur in the latter part of May or early in June, and again in the 

 middle of July. 



In 1916, as my investigations did not start until July, I consequently missed 

 the first flight, but I witnessed the second which was on July 20. In 1917 the first 



