THE MONTHLY BULLETIN. 647 



Crude Oil Emulsion. 



Some preliminary work was done to determine the effect of a good 

 crude oil emulsion upon the eggs. These tests while not extensive 

 enough for definite conclusions, indicated that such an emulsion would 

 give excellent results. Two strengths were used, viz, 12^ and 16| per 

 cent. No specific gravity test was made of this oil. It was, however, 

 the crude product just as it was pumped from the wells at Florence, 

 Colorado. It is very probable that any of the good distillate or crude 

 oil emulsions that are used successfully in the control of scale insects 

 in California could be used to good advantage in destroying leaf-roller 

 eggs also. 



Lime and Sulphur Useless. 



Owing to the fact that lime and sulphur has often been suggested 

 as a remedy it seems well to mention in this article, the fact that many 

 careful experiments have proven beyond a shadow of a doubt that 

 this preparation is of no value at any strength in destroying leaf- 

 roller eggs. 



SPRAYS TO KILL LARV/E. 



As the larvse feed upon the foliage it would seem that they could 

 be easily controlled by means of an arsenical spray. They are found, 

 however, to resist much stronger doses of arsenate of lead, etc., than 

 many others of our chewing insect, e. g., codling moth. It is possible 

 to kill quite a large percentage of the worms when they are small, by 

 very heavy applications of an arsenate of lead spray used at the 

 strength of three pounds to fifty gallons of water. Trees when sprayed 

 should be thoroughly drenched. It is important also that spraying 

 begin just as soon after the eggs have begun to hatch as possible. 

 Roughl}" speaking this will be very soon after the leaves have begun 

 to come out in the spring. A second application should be made in 

 the case of apples just before blooming and after the buds in the blos- 

 som clusters have separated one from another. The object of a spray 

 at this time is to cover the entire surface of the blossom cluster with 

 the poison in order that many of the larvae which ordinarily feed upon 

 the blossoms may be killed. The third arsenical spray for leaf-rolier 

 on apple trees will serve the dual purpose of a leaf -roller and codling 

 moth spray and should be applied when 90 per cent of the petals have 

 fallen and before the calyx cups close. Later sprays will do little or 

 no good in controlling the pest, as the worms become very resistant to 

 the poison as they get larger, and are well protected by curled leaves. 



Black Leaf " 40 " was used with good success in the experimental work 

 in Colorado, when the worms were very small. Two applications made 

 at the time indicated for the first two arsenical sprays will kill a large 

 percentage of the larv^. It should be used at the strength of one part 

 of Black Leaf "40" to eight hundred parts of water. 



SPRAYING MUST BE THOROUGH. 



Too much stress can not be placed upon thoroughness in spraying 

 for this pest. They are so well protected by the folds of leaves in which 

 they feed that it is only by the use of very heavy, drenching sprays that 

 the larvge may be killed. This does not apply so much to the spray to 

 kill the eggs although in this case every mass missed endangers the tree 

 that much more, and it does not take many of them when they hatch 

 to produce enough larvae to infest a tree seriously. 



