134 



Weldon (G. p.). Thrips Injury to Peaches in Southern California. — 



Jl. Econ. Ent., Geneva, N. Y., xiv, no. 5, October 1921, 

 pp. 424-428. [Received 13th January 1922.] 



In 1920 serious injury by thrips was caused to peaches in Southern 

 Cahfornia. Nectarines and plums, and to a less extent apricots, were 

 also attacked. The thrips enter the blossoms as soon as they appear, 

 and both adults and larvae feed on these until the husk is shed from 

 the young peach. After the peaches have reached a considerable 

 size, many thrips are found in the tender growth at the tips of the 

 twigs. The character of the injury varies, and is apparently some- 

 what influenced by the variety of peach. Although it does not 

 seriously impair the quality of the fruit, it makes it difficult to remove 

 the skin for canning purposes and thus lessens its value. Spraying 

 with nicotine sulphate distillate emulsion mixture did not prove 

 successful, owing to the protection afforded by the stamens and pistil 

 of the peach blossom, nor could the spray be got under the dried-up 

 blossom or husk. Various strengths of Nicodust also gave negative 

 results. 



The species concerned has not been definitely identified ; it is 

 thought by some to be Eiiihrips tritici, but others, including the 

 author, are inclined to the behef that it is E. helianthi. A species 

 possibly identical with it has also been found feeding on apples. 



Penny (D. D ). The Results of using certain Oil Sprays for the Control 

 of the Fruit Tree Leaf-roller in the Pajaro Valley, California. — 



//. Econ. Ent., Geneva, N. Y., xiv, no. 5, October 1921, 

 pp. 428-433. [Received 13th January 1922.] 



Oil spraying for the control of Tortrix [Ar chips) argyrospila, Wlk., 

 in apple orchards has been only partly successful. The chief reason 

 was probably the use of oils not especially adapted to leaf-roller 

 control. It is possible that in cases where negative results were 

 obtained the Western or asphaltum type of oil was used rather than 

 the Eastern or paraffin type. The differences in the action of these 

 oils was recorded by List [R.A.E., A, ix, 153], and several tests 

 with samples of both oils were conducted during the winter of 1920-21. 

 The technique employed is described. Most of the emulsions tested 

 contained 2-5 per cent, of cresol soap as the emulsifying agent. The 

 most satisfactory results were obtained with Pennsylvania gas oil, 

 a 10 per cent, solution killing 80-9 per cent, of the eggs sprayed. 

 Pennsylvania crude oil in both types of emulsions gave good results 

 in 10 per cent, and 15 per cent, strengths. Cahfornia distillate gave 

 practically no control. The kiUing efficiency of the Ortho brand of 

 Western crude oil emulsion varies more or less directly with the 

 percentage of oil in the mixtures. A 15 per cent, emulsion killed 

 almost 100 per cent., but a 12 per cent, one was not entirely satis- 

 factory. Further experiments on these lines are to be carried out 

 in the coming season. Crude oil emulsions are widely used in the 

 Pajaro Valley as general winter sprays because of the marked tree 

 stimulation they produce and their effect on many scale-insects. 

 The use of these emulsions would become even more general if they 

 were found to be effective against leaf-rollers at a strength within 

 reasonable cost. 



