STATE HORTICULTURAL SOCIETY. 97 



not be very great, and the whole thing could be accomplished by one 

 operation. The question is, would this application injure the trees. My 

 experiments go to show that it would not ; but these experiments have 

 not been conducted upon a sufficiently large scale to give entire confi- 

 dence. The full trial which I was upon the point of giving to this 

 method, in my fellow-townsman's orchard, was prevented and rendered 

 unnecessary by the sudden and unexplained disappearance of the canker 

 worms from it. Upon visiting the orchard in the present spring of 1873, 

 shortly after the usual time of egg deposit, and after an hour's diligent 

 search, only two or three clusters of the eggs could be found. What had 

 become of the insects and their eggs we could only conjecture. One 

 possible explanation was that the worms had destroyed the foliage so 

 early in the previous season that they failed to become matured. Another, 

 and we think more probable explanation was that the worms may have 

 been destroyed by blackbirds, large flocks of which the owner recollected 

 to have seen frequenting the trees the previous summer ; or they may 

 have been destroyed by parasitic enemies, several species of which are 

 known to infest them. This experiment, however, I hope, at an early 

 day, to see put to a thorough trial. 



Fourth — The Oyster Shell Bark Louse. I can dwell but a few 

 moments upon this long and well known insect. The oyster shell bark 

 louse has always been regarded as an impotted species, but they are 

 sometimes found in situations to which it is very difficult to explain how 

 they got access, if they come from abroad. The uncertainty is enhanced 

 by the difficulty of distinguishing and identifying closely allied species of 

 insects, when they occupy a low place in the scale of insect life, and when 

 in consequence of the simplicity of their organization, but few salient 

 points of comparison exist. There are several species of the genus Myt- 

 ilaspis, to which the apple bark louse belongs, one of which is found 

 upon the linden or bass wood, and another upon the Persian lilac, which 

 so closely resemble the apple species that it is impossible to tell whether 

 they are really distinct species, or only plant varieties of the same ; and 

 the same uncertainty exists respecting many allied species in the exten- 

 sive family of Aphides, or plant lice. The common bean aphis, for exam- 

 ])le, has been described as a distinct species, under no less than sixteen 

 different names, taken from the plants on which it happened to feed. It 

 is known to most persons who have taken an interest in such enquiries, 

 that for some ten years or more, the oyster shell bark louse has been on 

 the decline. There is no reason to suppose that this has been owing in 

 any appreciable degree to climatic influences. The known number and 

 activity of its insect enemies, both predaceous and parasitic are fully suf- 

 ficient to account for it. Its destruction, south of the 42d parallel of 

 latitude, has been almost complete ; and north of that line, it appears to 

 be in process of diminution, if not of absolute extinction. 



In this removal of what was once the most dreaded scourge of the 

 orchardist, man himself has played but an insignificant ])art. His reme- 

 dial appliances have been scattered, intermittent, i)artial, and altogether 

 inadequate. He has, indeed, done little more than look on, a deeply 



