INJURIOUS INSECTS OF 1904. 



91 



appeared and sprayed with the Caustic Lime, say about three timeSj 

 there would have been but a few hoppers. Some varieties appear 

 to be more afifected than others. * * * I am yet of the opinion that 

 if the dust or dry Bordeaux is as effective as the hquid, a tree can 

 be much more thoroughly sprayed than with liquid, and in less time 

 and with less work." In a later letter Mr. Mohl states that he 

 sprayed the nursery only once, with Caustic Lime, after the hop- 

 pers appeared and that it did not destroy them. 



In certain experiments at the Station during the season, in con- 

 nection with the leaf hopper, we found that one part of emulsion 

 to twelve of water, when liberally applied to young nursery trees, 

 will sometimes slightly burn some of the leaves of young 

 apple trees if applied freely in hot sunshine. Under favorable con- 

 ditions, however, we have used it as strong as one to ten without 

 appreciable injury. 



Incidentally, observations were made upon the stability of kero- 

 sene emulsion when mixed with water. We found that when one 

 part emulsion was used to twelve of water, the separation of the 

 oil began immediately, and the mixture could not be used safely 

 after 15 hours; one part of emulsion to eight of water gave almost 

 as bad results, while one part of emulsion to six of water was very 

 much slower in separating. We found further that 10 per cent 

 Kero-water could be used with safety as regards the foliage, was 

 death to plant lice, and apparently fatal to old as well as young tree 

 hoppers. 



Fig. 88 represents the different stages of 

 this tree hopper from shortly after hatch- 

 ing to the adult stage. It has been found 

 on a number of trees and plants other than 

 apple. In the case of the latter tree it 

 would appear from evidence at hand that 

 the egg is laid by the adult in the tissue of 

 the leaf, since young are found on the un- 

 der side of the leaf, of such a tender age as 

 to preclude the possibility of their coming 

 ""ile LelfHllTer._''ETp!ascI ^^m any but a nearby source. Yet in the 

 mail. Osborn. Original. abscncc of couclusivc evidence the Ento- 



mologist hesitates to regard the above probability in the light of a 

 fact. 



