THE CANADIAN ENTOMOLOGIST. 



Fig. I.— -The Pear-tree Psylla — greatly 

 niagriified. 



Diirinsi the winter it secures shelter in the crevices of the bark on the trunks 

 ajid large limbs of the trees, in nearby 

 rubbish, or wherever it can find pro- 

 tection; hence the advantage of clean 

 culture, in which case it will be con- 

 fined to the trees. The small lemon- 

 coloured eggs are laid about the mid- 

 dle of April, and hatch about the 

 middle of May, according to weather 

 conditions (Figure z). There are 

 probably four broods in a season. When the nymphs appear, if there 

 be no foliage, they make their way into the opening buds. They secrete 



large quantities of honey dew, which 

 frequently drips from the leaves, and 

 gets over the whole of the tree and 

 fruit, in which a black fungus de- 

 velops. 



There is difficulty in treating the 

 Psylla during the summer. Except 

 immediately following a heavy rain, 

 the nymphs are usually so com- 

 pletely enveloped with honey dew 

 that spray will not reach them, and 

 the mature insects are so active 



that when spray strikes a tree they 

 instantly fly away, and do not return until the spraying is discontinued. 



An ounce of crude petroleum in the proportion of i in i6 (i gal. of 

 petroleum in 16 gals, of emulsion), has in my experience proved the most 

 satisfactory in case a treatment must be given in summer, but I would 

 depend upon a very thorough application of lime and sulphur (lime 30 

 lbs., sulphur 20 lbs., in 40 gals, of wash, cooked two hours), made \n 

 March, to wipe out the pest. At this season there are no eggs. The 

 overwintered adults are very sluggish, not at all like those of the summer 

 broods, and these alone are present. If the wash be driven well into all 

 of the cracks of the bark the destruction of the insects will be complete. 



l.ime alone will destroy P.sylla perhaps as completely as with sulphur 

 added, and will go a long way in cleaning off the black fungus, but lime 

 alone will not destroy scale insects, and these are invariably present. 

 Whether it be lime, or lime and sulphur that is used, the wash must be 

 liberally applied, for it will not diffuse, but remains where it strikes the 



a egg, b iiympli — 



Fig. 2.— Pear-tree Psylla 

 greatly magnified. 

 (Marlatt, U. S. Dept. of Agriculture.) 



tree, and if the Psylla is to be killed it must be hit, 



