65 



other insects, I am sure that, if these eggs had been killed by the soap, 

 they would have shriveled up to nothing in much less than a month 

 of such weather. But be this as it may, I shall be able to ascertain 

 in the spring of 1868, from the portion of the branch that remains on 

 the tree, whether these eggs that were soaped in K^ovember will hatch 

 out as usual in the following spring, or whether some or all of them 

 were killed by the soap. 



From the above facts, I infer that soap will kill Bark-lice when 

 they are very young, but has no effect whatever upon the matured 

 scale.* 



It is proper to add that, in all the above experiments that were 

 tried in June, there was no rain for at least 6 days afterwards; and that 

 in the November experiment there was no rain for several weeks after- 

 wards. So that the various articles applied had a sufficient time for 

 operating, before the rain washed them off. 



Statement 4th. — In April, 1866, I had an apple-tree, the lower 

 limbs of which were infested, some of them pretty badly, by the Oys- 

 ter-shell Bark-louse. I pruned them all quite closely, removing all 

 wood under one-half inch in diameter, and then with a common 

 painter's "sash-brush"' painted them all over as thinly as possible with 

 kerosene. Not many weeks afterwards I examined scores of the 

 scales on these limbs, and found the eggs under all of them dead and 

 dried up ; and not a single Bark-louse, so far as I could discover, sub- 

 sequently hatched out on them. Out of the whole number of limbs, 

 but a single one died, and that was so completely covered with scales, 

 that it would probably have died anyhow. The remainder put out fresh 



*Since the above was written^ Dr. Mygatt has informed me that pure, 

 undiluted soft soap is largely applied in his neighborhood to the matured 

 scale, under the erroneous idea that it destroys the eggs. He has been kind 

 enough to send me (February 29tli) an infested twig soaped in this manner, 

 and another twig cut off the very same limb which had not been soaped at 

 all. On lifting and examining under the lens 100 scales upon each of these 

 twigSj 1 found thai on the soaped twig there were 31 scales containing plump, 

 healtliy eggs, and 69 scales, mostly gutted by the Mites, which contained no 

 such eggs; while on the unsoapcd twigs the numbers were respectively 30 and 

 70; showing that, where the soap had been apj^lied, the number of healthy 

 normal scales was actually one per cent, greater than where natvire was left 

 to her own devices. In tJiis case the soap had been applied only 12 days 

 before I lifted the scales ; but in a specimen sent at the same time, to which 

 the soap had been applied for considerably more than a month, there was a 

 still larger proportion of healthy normal scales, namely, 37% per cent, in- 

 stead of 31 per cent. Hence, it may be infeired that even pure undiluted 

 soit soap produces no effect upon the matured scale; although, as Dr. Mygatl 

 informed me, "it kills all the foliage, fruit or j'oung growth that it touches." 



