THE INSECT WORLD. 



339 



The ' ' pear-midge, ' ' Diplosis pyrivora, is an imported species 

 appearing with the first buds of early spring and ovipositing in 

 them as soon as they begin to show white. The young larvae 

 make their way to the ovary or seed-capsule of the setting fruit, 

 and when this reaches the size of a nut, growth stops. The pears 

 are then irregular in shape, a little knotty, and filled in the centre 

 with a mass of orange-yellow larvae. In June these become full- 

 grown, leave the 

 pears, — which now 

 crack open . and de- 

 cay, — and drop to 

 the ground, beneath 

 the surface of which 

 they pass the winter. 

 The insect is es- 

 pecially fond of the 

 ' ' Lawrence' ' va- 

 riety, and where 

 such can be found 

 in sufficient num- 

 bers, all others are 

 exempt. The way in 

 which this species 

 can be controlled 

 is by treating the 

 ground beneath in- 

 fested trees with a 

 heavy top-dressing 

 of kainit, — say one 

 ton to the acre, — applied between the middle and end of June, 

 Planting ' ' Lawrence' ' trees as traps and applying the above 

 remedy to the soil beneath them will decidedly lessen the injury 

 to the balance of the orchard, or their fruit may be gathered 

 - and destroyed in May, with all the contained larvae. 



Not all the gall-midges are injurious, however. Many species 

 form galls or other distortions of growth on weeds or other plants 

 of no special economic interest, or in such a way as to cause no 

 real injury, and a few are actually predaceous and directly bene- 

 ficial. Such is the species that feeds in the Phylloxera leaf-galls 



Fig. 387. 



The pear-midge, Diplosis pyrivora.—a, female adult ; c, 

 pupa ; other references are to structural details. 



