95 



lead arsenate to 50 U.S. gals. Bordeaux mixture. Against the peach 

 borer [Aegeria exitiosa] tests with paradichlorobenzene have been 

 continued throughout the past three years. It is found that | oz. 

 to 1 oz. of the chemical appHed to each tree in the autumn after 

 oviposition will destroy about 95 per cent, of the larvae. Trees of 

 6 years or older are uninjured by this treatment, but younger trees, 

 on account of their thinner bark, have sometimes been damaged. 

 For plum curcuho [Conotrachelus nenuphar] and certain peach diseases 

 the dusting method seems to compare favourably with spraying, 

 even under the worst conditions. Measures against the Japanese 

 beetle [Popillia japonica], recently introduced from Japan into New 

 Jersey, are discussed [R.A.E., A, vii, 511]. 



Investigations into the value of various insecticides have been made, 

 including a study of the material known as derris [R.A.E., A, vii, 

 496]. Additional experiments have confirmed the conclusion that 

 calcium arsenate may always be substituted for Paris green, and that 

 for pomaceous fruits it forms a good substitute for lead arsenate when 

 used with hme or fungicides containing lime. Studies of insect- 

 destroying fungi have been continued, especially regarding a fungous 

 disease of cutworms and an obscure disease of the periodical cicada 

 [Tibicen septemdecim]. 



The conditions in regard to the sweet potato weevil [Cylasformicarius] 

 in various locaHties are discussed and the method of dealing with the 

 pest in each, under a fiscal grant of about £10,000, is outhned. Other 

 vegetable pests include the potato aphis [Macrosiphum solanifolii], 

 which was unexpectedly abundant and was controlled by strong 

 nicotine sprays. The bean ladybird [Epilachna corrupta] has been 

 controlled by lead arsenate and zinc arsenite sprays. The great 

 increase in bean-growing, owing to War conditions, has resulted in a 

 corresponding increase in the numbers of the com earworm [Heliothis 

 obsoleta], which seriously injured the crop, and with the reduction 

 of the bean acreage this season serious damage is Ukely to result 

 from the abundance of the pest. The pea moth \Cydia nigricana'l] 

 is increasing to a serious extent, having been imported from Canada into 

 Wisconsin. It has been demonstrated that the celery leaf-tier [Pionea 

 ferrugalis] can be controlled by spraying with 1 lb. lead arsenate to 

 50 U.S. gals, of water, the first treatment being made when the eggs 

 are hatching and being repeated every two weeks. The cost of this 

 treatment, which was continued until the insects had disappeared, 

 was about 8s. per acre. 



Exhaustive studies have been made of insects aSecting forest trees 

 and much new information has been gained. The inter-relations of 

 forest fires and insects have been studied on an area of about 8,000 

 acres in southern Oregon. This area had been under observation 

 since 1914 and the fire had burned over it in 1918. Records show 

 that previous to the fire the insects had killed 485,000 board feet 

 of timber. The fire killed 170,000 feet and subsequently the slightly- 

 fire-injured as well as the uninjured trees in the burned area were 

 killed by beetles attracted from the surrounding areas. Infestation 

 in the burned area increased more than 1,000 per cent., but decreased 

 in the surrounding areas. The broods of the beetles in the fire- 

 scorched trees did not increase to any appreciable extent. The 

 fire therefore, contrary to expectations, did not contribute to an 



