THE CHERRY FRUIT SAWFLY. 



79 



material. It is possible that this species is rather heavily para- 

 sitized at times. The insect has been known in the Suisun Valley 

 since 1905, but caused comparatively little injury from that time 

 until the serious outbreak of 1909. As no spraying had been done 

 in the infested orchards that would be of any value as a control to 

 this particular species it would seem that the parasites, together with 

 more thorough cultivation, have served to keep it fairly well in check. 

 The insect was less numerous in 1910 than in 1909 and the same was 

 true of the years 1911 and 1912. 



EXPERIMENTS IN CONTROL. 



Experiments in spraying with arsenate of lead were made in 1910, 

 but in this instance the poison did not prove to be altogether effec- 

 tive. Some larvae were killed, but not enough to warrant the recom- 

 mendation of this as a satisfactory treatment in case of a serious out- 

 break of the insect. Further work along this line is desirable. Mr. 

 O'Gara, in a letter, reports satisfactory results from the use of arse- 

 nate of lead in the Rogue River Valley of Oregon. 



Many adults were killed in the early mornings while spraying with 

 3 per cent distillate-oil emulsion to which sulphate of nicotine had 

 been added at the rate of 1 part to 2,000 parts of water. This 

 method would most likely be a very effective means of control if all 

 the spraying could be done in the early morning. At this time the 

 adults are very sluggish and can be easily wet with the spray. 



Perhaps a more likely means of holding this sawfly in check is by 

 careful cultivation. The most serious hindrance to this plan of 

 treatment in cherry orchards is that the roots of the cherry tree close 

 to the trunk are near the surface, and some larvae go below the top of 

 these roots. However, it is highly advisable to cultivate the land 

 thoroughly two or three times just prior to the first picking of the 

 Black Tartarian cherries, as most of the larvae are leaving the trees 

 -at this time and numbers of them would probably be killed. 



ADDITIONAL COPIES of this publication 

 -L\- may be procured from the Superintend- 

 ent of Documents, Government Printing 

 Office, Washington, D. C, at 5 cents per copy. 



