225 



oil the 9th and 14th of April, and while the spray destroyed the adults 

 which it struck, the eggs were somewhat variously affected. Many of 

 the lice received with check lots from uiisprayed trees failed to hatch 

 in both instances, the death of the leaf seeming to affect tlie vitality of 

 the insect. 



Several satisfactory lots were received later, however, from which by 

 comparing the hatched with the nnhatched eggs we were able to ap- 

 proximate the proportion destroyed by spraying. Thus, on May 6 two 

 batches of leaves were received, the one from unsprayed trees and the 

 other from sprayed trees. On eight leaves of the si^rayed lot there were 

 approximately 20,500 eggs, ranging from 1,000 to 5,000 on each leaf. 

 Of these 1,230 had hatched, or about one-sixteenth, while upon the check 

 leaves unsprayed the proportion of hatched eggs ranged from one-half 

 to three-fourths of the whole, the remaining ones being still sound. It 

 must be remarked further that only a small proportion of the larvae 

 which had hatched from the eggs upon the sprayed trees had settled 

 and appeared in a healthy condition, but owing to the fact that the 

 leaves were plucked and transmitted through the mail, we are unable 

 to state the precise significance which this condition of affairs may 

 have. It was noticed, however, that upon the unsprayed leaves a con- 

 siderable portion of the larvie were still present, some already in the 

 second stage and apparently in a healthy condition. 



Another spraying was made by Mr. Foster upon May 4, at which 

 date the majority of the eggs had hatched. Here again transmission 

 through the mail dissipated any exact conclusions to be arrived at from 

 the office examination, but the indications all favor the conclusion that 

 the spraying was successful. Large numbers of egg shells were found 

 upon leaves sent in after this spraying, but very few larva' were found. 

 The great majority had apparently been killed and had dropped. Of 

 those which settled the greater number were dead and had turned 

 brown and at least one-half of the few still alive were apparently affected 

 by the emulsion. In round numbers about one-tenth of one per cent of 

 the hatched larv^ were still living and as just stated only about one- 

 half of these appeared healthy. 



From these experiments we may state that the best time to spray is 

 after the eggs have hatched, and we may approximately indicate as the 

 best means of selecting the proper time, say three weeks after the bulk 

 of the adult insects of the spring brood are seen to be flying about the 

 trees. This should be supplemented by spraying at the corresponding 

 period in September, and as a result the numbers of the insects will 

 probably be reduced to such an extent that they will do little injury 

 the following year unless the trees are again stocked irom neighboring 

 unsprayed groves. 



NATURAL ENEMIES. 



The ordinary scale-feeding insects, so many of which have been enu- 

 merated in Mr. Hubbard's report on insects affecting the Orange, feed 

 18430— Ko. 4 2 



