448 



Parrott (P. J.), HoDGKiss (H. E.) & Lathrop (F. H.). Plant Lice 

 Injurious to Apple Orchards, ii. Studies on Control of Newly- 

 Hatched Aphides.— iVew; York Agric. Expt. Sta., Geneva, Bui], 

 no. 431, March 1917, pp. 33-79, 1 plate, 4 figs. [Received 3rd 

 August 1917.] 



This paper, which is a continuation of an earlier one [see this 

 Review, Ser. A, iv, p. 273], records the results of further studies in 

 the life-history of the apple Aphids, Aphis sorhi (rosy aphis), A. pomi 

 (green aphis) and A. avenae (oat aphis), and of experiments for the 

 development of more efficient spraying against them. At the beginning 

 of the infestation in 1916, the oat aphis was the most abundant in the 

 majority of orchards. The relative abundance of the three species 

 exhibits a seasonal cycle which, while probably varying somewhat 

 from year to year, appears to be fundamentally constant. 



Experiments were made in artificially infesting certain fruit-clusters 

 with examples of each of the three species, these clusters being encased 

 in bags, while others were kept free from any infestation in a similar 

 manner, as a control. Both A. sorhi and A. pomi severely damaged 

 young foliage, while the infestation of A. aveime, although severe, was 

 less lasting and showed very little injury to the fruit. The attack of 

 A. sorhi was found to increase the number of fruit-clusters, the fruit 

 however dropping before it was ready for picking. Fruit that suffered 

 from the attacks of A. pomi was frequently contorted and dropped 

 from the tree. All infestation resulted in diminution in the size of the 

 fruit, the attacks of A. sorhi being the worst in this respect. A graph 

 shows the comparative growth of normal and infested apples. 



Spraying experiments with a mixture of f pint nicotine (40%) to 

 100 U.S. gals, lime- sulphur solution (1 to 8), applied as a delayed 

 dormant spray in May, revealed the susceptibility of the rosy aphis 

 and the oat aphis to this form of spray. The trees so treated were free 

 also from the green aphis until June, when there was a re-infestation 

 due to invasion by winged migrants. The results of these, as well as 

 certain auxiliary experiments, are given in tables. Further experiments 

 are advised with this delayed dormant spray, which is postponed until 

 after the eggs of the rosy aphis have hatched. The disadvantages of 

 delaying the operation, the chief of which is the possible injury to 

 foliage, are pointed out, but it is considered that on the whole the 

 advantages outweigh the disadvantages. As the damage by these 

 Aphids varies according to locality and seasonal conditions, it is 

 suggested that each grower should test the efficacy of such treatment 

 over a period of years on a part of his orchard, before making it a 

 regular procedure. 



Back (E. A.) & Pemberton (C. E.). The Melon Fly in Hawaii.— Z7./S. 

 Dept. Agric, Washington, B.C., Bull. no. 491, 30th June 1917, 

 64 pp. 24 plates, 10 figs. [Received 3rd August 1917.] 



Dacus (Bactrocera) cucurhitae, Coq. (melon fly), is the most 

 important pest of cucurbitaceous crops in the Hawaiian Islands, 

 particularly as it attacks with the greatest persistency such crops as 

 squashes, pumpkins and vegetable marrows, which would otherwise 

 furnish an abundant food supply for the poorer classes. No part of 



