118 The Ottawa Naturalist [Sept. 



The figure herewith gives a good idea of the size and ap- 

 pearance of the moth. As its name impHes, it is pure white, 

 expanding about an inch and a half when the wings are spread. 



In the United States, the caterpillar of this moth has, on 

 many occasions, appeared in very destructive numbers, and, 

 on account of its injuries to the elm and being one of the measur- 

 ing-worms, it has been called the Elm Span-worm. Its injuries 

 to shade trees, particularly elm and basswood, in some of the 

 larger cities, have been specially reported upon by several 

 observers. It is also recorded as an apple tree pest. 



The female moth, soon after emerging from the pupa, lays a 

 large number of eggs .usually on the underside of the branches of the 

 trees. The eggs remain on the liinbs until the following spring, 

 only hatching, it is stated, when the leaves unfold, the 

 young caterpillars feeding on the new and tender foliage. 

 In from five to six weeks from hatching the caterpillar has 

 reached its full grow-th, and in colour resembles the twigs of the 

 tree on which it has been feeding, the body being brownish; the 

 large head and terminal segment of the body are bright red. 

 When mature the larva changes to the chrvsalis state, and in 

 about 10 days the moth emerges. 



The sudden great abundance of this insect on the above 

 evening was certainly remarkable and very extraordinary. Not 

 a single specimen of the larva was seen in the Ottawa district 

 during June or July by any of the officers of the Division of 

 Entomology, or by other local entomologists, and it would be 

 most interesting to know where all the moths came from. 



The sparrows of the city had a great feast early the follow- 

 ing day. Along the main streets, the wings of the moths were 

 very noticeable, the bodies having been eaten. 



In an article on the White-marked Tussock Moth, Dr. 

 E. P. Felt, in his "Insects Affecting Park and Woodland Trees," 

 says: "Dr. J. L. Le Conte has placed on record an interesting 

 instance of the effect this bird mav have on our local fauna. 

 He states that the English sparrow was imported for the purpose 

 of keeping in check the Snow-white Linden Moth, Ennomos 

 subsignarius, Hbn., and that in Philadelphia, after the sparrows 

 had destroyed the Ennomos larvae, the White-marked Tussock 

 Moth caterpillars found abundant food, and being unmolested 

 by the sparrow, on account of their irritating hairs, they soon 

 became even worse pests than the other species." 



Since the above article was prepared, similar visitations, in New York State, of 

 apparently the same moth, have been reported in the daily press and certain agricultural 

 papers. — Ed. 



