33 



plants from the ravages of the adult beetles until sufficient foliage is 

 developed for the application of the liquid sprays, which should be 

 used as soon as the plants are from 4 to 8 inches high. These should 

 be applied at least every 10 days and preferably once a week until the 

 crop is ready for harvest. Applying the spray between 9 a.m. and 

 4 p.m. on bright, clear days, will, to a great extent, eliminate the 

 danger of scorching. The spray should be applied in as fine a mist 

 as possible, so that both sides of the leaves will be coated with the 

 liquid. A high-pressure sprayer is therefore more satisfactory. Great 

 care should be exercised in the mixing and preparation of the spray 

 materials, as many good crops have been ruined through carelessness in 

 this respect. 



Davis (J. J.). The pea aphis with relation to forage crops. — U.S. Dept. 

 Agric, Washington, D.C., Bull. no. 276, 29th September 1915, 

 67 pp., 17 figs. [Received 22nd November 1915.] 



In the United States, Acyrthosifhon (Macrosiphum) ptisi, Kalt. (pea 

 aphis), seems to have made its first appearance in destructive and 

 noticeable numbers in 1899, although it is known to have been present 

 there for at least twenty years previously. The present paper discusses 

 the identity of this species [see this Revieiv, Ser. A, iii, p. 702] and gives 

 an account of extended investigations on the life-history. Macrosiphum 

 trifolii, Perg., is considered to be identical with A. jnsi. The following 

 is a list of the authentic food-plants of this Aphid in the United States : 

 Capsella bursa-pastoris (shepherd's-purse), Ervum sp. (lentil), Lathyrus 

 odoratus (sweet pea), L. sativm (grass pea), Medicago saliva (lucerne), 

 Melilotus alba (white sweet clover), Pisum sativum (garden pea), 

 Trifolium incarnatum (crimson clover), T. pratense (red clover), 

 T. repens (white clover), Vicia ludoviciana, V. gigantea, and 

 V. villosa (vetches or tares). Clovers serve as hosts for this Aphid 

 throughout the year, and it is on these plants that it usually passes 

 the winter, either as an egg or as a viviparous female ; during the 

 summer months, the migrants also pass to other leguminous crops 

 and on these they multiply very rapidly, often destroying large acreages. 

 In the latitude of La Fayette, Ind., A. pisi winters both as a viviparous 

 female, usually wnngless, and as an egg. Farther north it probably 

 winters exclusively in the egg-stage, while further south, in the latitude 

 of Tennessee, the sexual forms which lay the hibernating eggs are rare. 

 Still further south, only the viviparous females occur and it is believed 

 that viviparous reproduction may occur indefinitely in localities 

 where the winters are sufficiently mild. In the latitude of Illinois, 

 Indiana, Maryland and Delaware, migrants from the winter hosts (red 

 and crimson clovers) begin to spread to new fields of clover and garden 

 peas about 1st May, and injury usually becomes noticeable about 

 1st June, extending up to July. By that time, parasitic and predaceous 

 enemies are sufficiently numerous to control the Aphid, or at least hold 

 it in check, and a little later the fungus, Empusa ajjhidis, becomes 

 prevalent, so much so that the pest may appear to be exterminated. 

 As weather conditions become more favourable for the Aphid and less 

 so for its enemies, it is usually again abundant by September on clover 

 and late, garden peas. Further north, the insect does not appear in 

 injurious numbers until about July. Experiments carried out at 



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