196 EXPERIMENTAL FARMS 



3-4 EDWARD VII., A. 1904 



tree is touched, of drawing in the legs and falling to the ground. There are two 

 broods in a season, the flies of the first brood appearing and laying their eggs early in 

 June. These are inserted into the tissues of the leaf, where they remain for about a 

 fortnight before the young slugs hatch. The greatest injury is done to fruit trees dur- 

 ing July. The larvse are sometimes, and indeed very frequently, in such enormous 

 numbers as to strip the green cellular tissue from the leaves to such an extent that the 

 foliage of whole trees and even of orchards is destroyed, and the trees are left appa- 

 rently covered with only dead leaves. This injury, occurring as it does when the trees 

 require the full use of their leaves to bring the fruit to perfection, is a serious one, 

 and its effects last .over and affect the crop of the second year. A second brood of 

 larvse appears in Aug-ust and September. These, when fully fed, fall to the ground and 

 penetrate a short distance beneath the surface, where they remain until the following 

 J ear, changing to pupas about the middle or end of May, and the flies emerge soon 

 afterwards. iThe Pear-tree Slug, which, as its latin name indicates, attacks also the 

 Cherry-tree, is a very easy insect to control. In properly managed and sprayed orch- 

 ards it can never be troublesome. Owing to the viscid secretion on the skin any dry, 

 dusty material adheres to it and causes the insect great inconvenience; therefore, dust- 

 ing trees with freshly slaked lime or even with finely sifted road dust, will have the 

 effect of clearing trees of large numbers. Two or three applications should be made at 

 short intervals. In hot, dry weather dusting trees either by hand or with an insect 

 gun or other implement for the distribution of dry powders, for two days running, I 

 have found quite satisfactory. The material used was freshly slaked lime, to which 

 Paris green was added in the proportion of one pound to fifty, so that in case any of 

 the larvse, which might have been moulting, escaped, there would still be on the foliage 

 poison to destroy them as soon as they began to feed. The most practical remedy is 

 undoubtedly to spray trees with Paris- green or some other arsenical insecticide, one 

 pound to 160 gallons of water. This treatment will not only destroy the Pear-tree Slug 

 but also many other kinds of leaf -eating insects. 



The Pear-tree Flea-louse {Psylla pyricola, Foerster). — Although up to the present 

 time the Pear-tree Flea-louse, called also the Pear-tree Psylla, has not been the cause 



of widespread injury, still there are every year com- 

 plaints of more or less serious loss in pear orchards 

 in western Ontario. I have found this insect to 

 Ibe abundant when looked for in orchards, throiigh- 

 cut the Niagara district and along the north shore 

 of Lake Erie. During the last summer I have had 

 it sent to me from two localities in Nova Scotia, 

 and believe it to be also present at other places 

 from which no specimens have been received. Prof. 

 Fig. 18.— The Pear-tree Flea-louse : Lochhead, of the Ontario Agricultural College, 

 perfect insect— enlarged. writes me as follows : — 



* This insect has been very injurious this past season, more especially in the 

 Grimsby district.' A correspondent writes : — ' When I came home on July 4, many 

 trees were fairly covered with it. The insects were mostly wingless, with a few winged 

 forms. They are found in the axils of the leaves, along the petiole and along the 

 blade, but are chiefly found on the leaves a short distance from the vein or just in the 

 axils of the secondary veins or mid-veins. In the first place, the tissue of the leaves 

 dries up in spots where they are situated; but in the latter case they cause a drying 

 ct the tissues along the edge of leaf at the outer extremity of the vein. When the 

 psylla is situated in the secondary axils of the leaf, the petiole seems yellowish in 

 colour and the attachment to the stem seems weak. About July 15 to 25 the psyllas 

 were most abundant — the number of winged forms increasing until the 25th. A 

 heavy rain on the 23rd cleared the trees of the honey-dew, and seemingly of quite a 

 number of the psyllas. After another heavy rain on the night of July 27', I noticed 



