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5. — The Pear-tree Slug-worm. — Selandria crrasi, Curtis. 



In 1874, as Mr. Saunders relates in his very complete account of this insect in our 

 Report for that year, the slug-worms were unusually abundant on pear-trees in the neigh- 

 bourhood of London, Ontario, in many cases destroying the foliage so thoroughly, that 

 " they looked as if they had been scorched by a fire, every leaf in some instances dropping 

 from the trees, so that for a time they were as bare as in mid-winter." Such a visitation, 

 happily, is not common ; still these disgusting creatures are usually to be found more or 

 less every year on our pear and cherry trees. In Scotland, in 1880, they appear to 

 have been numerous and destructive both at Dalkeith and Dumfries. 

 Fig. 50. rpj^e 



-worms feed on the upper surface of the leaves of the pear 

 and cherry, eating away the whole of the soft substance of the leaf, so 

 that the veins and the skin of the lower side are all that remain. They 

 may be recognized, when at their work of destruction, by their blackish 

 or bottle-green colour, together with their peculiar shape, and the cover- 

 ing of slime or moisture exuding from their skin, which gives the worms 

 the appearance of a slug, or rather that of a lump of wet black dirt 

 fallen on the leaf and run together at one end. They may be at once 

 recognized also, when very numerous, by their disgusting and sickening 

 smell. 



Miss Ormerod relates that, in England, " the sawflies appear in 

 July, and deposit their eggs on or in the upper side of the leaf ; these 

 eggs are oval, and hatch in a few days. The larvae are of the lumpy 

 shape figured above, much the largest at the back of the head ; they are 

 furnished with ten pairs of feet — that is, one pair on each of the three 

 segments next to the head, and a pair of sucker-feet on each of the other 

 segments, excepting on the fourth from the head and the tail segment, 

 which are footless. When feeding, they keep the end of the tail a little 

 turned up. In four or five weeks these slug-worms arrive at their full 

 growth, which is about half an inch in length, cast their dark bottle- 

 green skins, and appear as yellow or buflf caterpillars, free from all shine, 

 A leaf attacked by and transversely wrinkled, instead of being perfectly smooth. In the 

 a M^?nifieT?'eci i'^^*^^*^® noted this happened at the beginning of October, and the cater- 

 °men. pillars shortly after left the leaves and went down into the ground, 



where they spun an oval brown silken cocoon covered outside with earth, from which 

 the sawflies came up in J uly in the following year. The female fly is of a shining black, 

 tinged with violet ; the wings often stained with black, with dark nerves, and a dark 

 brown mark (the stigma) along the fore edge. The four anterior legs are brownish ochre, 

 and the others are more or less of that colour, but generally much darker ; and the thighs, 

 or at least the base, are pitch colour." 



In Canada these saw flies are double-brooded. The winged flies appear in May ; 

 the eggs are deposited singly in little slits cut for them in the skin of the leaf by the 

 ovipositor of the female, and these produce a brood, coming out in the perfect state in 

 July ; from which a second brood arises, which is full grown in September or October. 

 These remain in the ground during the winter, and for the most part appear (as above 

 mentioned) fully developed in the following May ; but some remain in the ground 

 unchanged till the following year. 



As a prevention. Miss Omerod recommends the same plan as in the case of the 

 gooseberry saw fly, viz., to skim off" the surface soil beneath the infested trees, and get 

 rid of it so as to destroy the contents. The cocoons are stated to be at a depth of from 

 one to three or four inches below the surface, according to the nature of the soil. She 

 suggests as remedies, (1) Shaking the flies down from the trees early in the morning 

 or late in the evening (or at whatever time it was found they were collected on the 

 leafage), and catching them on boards covered with wet tar, or cloths, taking care that 

 they were destroyed before they could escape ; (2) Dusting with caustic lime two or 

 three times ; (3) Syringing with tobacco water, strong soapsuds, etc. ; and (4) Showering 

 the trees with a solution of hellebore. 



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