26 PROTECTION OF PLANTS, 1916-17 



the flies, the progenitors of the mischievous brood of slugs, appearing on 

 the wing in the Northern States and Canada from about the third week in 

 May until the middle of June. The fly is of a glossy black colour with four 

 transparent wings, the front pair being crossed by a dusky cloud; the veins 

 are brownish and the legs dull yellow, with black thighs, except the hind 

 pair, which are black at both extremities, and dull yellow in the middle. 

 The female fly is more than one fifth of an inch long, the male is somewhat 

 smaller. 



"These flies are called 'saw-flies' from the fact that in most of the species 

 the females are provided with a saw-like appendage at the end of the body, 

 by which slits are cut in the leaves of the trees, shrubs or plants on which the 

 the larvae feed, in which slits the eggs are deposited. The female of this 

 species begins to deposit its *eggs early in June; they are oval and placed 

 singly within little semicircular incisions through the skin of the leaf, some- 

 times on the under side and sometimes on the upper. In about a fortnight 

 these eggs hatch. 



"The newly-hatched slug is at first white, but soon a slimy matter 

 oozes out of the skin and covers the upper part of the body with an olive- 

 colored sticky coating. After changing its skin four times, it attains the 

 length of half an inch or more and is then nearly full-grown. (It requires 

 four or five weeks for the slug to make those changes of skin). 



"After the last moult, it loses its slimy appearance and dark colour, 

 and appears in a clean yellow skin entirely free from slime. In a few hours 

 after this change it leaves the tree and crawls or falls to the ground, where 

 it buries itself to a depth of from one to three or four inches. There the 

 insect changes to a chrysalis, and in about a fortnight finishes its trans- 

 formation, breaks open its earthen cell, crawls to the surface of the ground, 

 and appears in the winged form. 



"About the third week in July the flies are actively engaged in depositing 

 eggs for a second brood, the young slugs appearing early in August. They 

 reach maturity in about four weeks, then retire under ground, change to 

 chrysalids, and remain in that condition until the following spring." 



Saunders, as quoted above, says that there are two broods of the pear 

 slug in one season, but in our orchards at Saint-Denis in Kamouraska we 

 have never seen more than one brood, the first slugs appearing with us at 

 the beginning of August. This covers an experience of twenty-three years. 



To destroy this slimy larva it is advisable to dust freshly slaked lime 

 on the leaves of the trees infested. 



