MISCELLANEOUS INSECTICIDE INVESTIGATIONS. 19 



of calcium, commercial, produced 77.34 per cent of sound fruit, 

 about an average of the efficiency of the two homemade prepara- 

 tions. The slight burning effect on the foliage amounted to about 

 the same as on the homemade arsenate of calcium plats. Arsenite 

 of zinc powder, commercial, produced 91.11 per cent sound fruit. 

 This material produced moderate burning, about 20 per cent of the 

 leaves being more or less spotted by the spray. Arsenate of zinc, 

 homemade, produced no burning of the foliage and held the codling 

 moth to 84.95 per cent free from worms. The unsprayed plat 

 averaged 47.64 per cent of fruit free from codling-moth injury. 



EXPERIMENTS, 1914. 



Experiments with various insecticides, alone and combined with 

 fungicides, were made, both at the laboratory and in the field, during 

 the season of 1914. The investigations were continued along the 

 same lines as during the two previous seasons. 



The field experiments were conducted in the J. T. Beckwith apple 

 orchard, the John Hamilton pear orchard, both of Benton Harbor, 

 Mich., and the William Birkit vineyard, located at Glenlord, Mich. 

 The field experiments were on a relatively large scale, so that the 

 results represent what may be expected on a commercial basis. 



LABORATORY TESTS. 



The fall webwoim (Hypliantria cunea Drury) was not so abundant 

 as during the seasons of 1912 and 1913, and it was not always possible 

 to secure a sufficient number of young larvas for the poison-feeding 

 tests. Consequently, when larger larvse were used, the strength 

 of the poisons was increased to accelerate the killing of the larvse. 

 However, the same size of larva was used in all lots in each experi- 

 ment, and the results are therefore comparative. 



The laboratory experiments included commercial and homemade 

 insecticides, used alone or combined with a fungicide. Wild-cherry 

 twigs were sprayed by means of a hand atomizer and the spray mate- 

 rial allowed to dry thoroughly before placing the larvse upon the host 

 plant. Time did not permit daily observations, and accordingly the 

 results do not always represent close comparisons, but from a prac- 

 tical point of view they are sufficient. 



Experiment XI. 



VARIOUS ARSENICALS ALONE AND COMBINED WITH OIL EMULSIONS AGAINST LARViE OF 



THE FALL WEBWORM. 



The chief object of this experiment was to ascertain whether the 

 combining of arsenate of lead with kerosene emulsion would affect 

 the individual value of either material for insecticidal purposes. 



