156 



PLUM. 



On the 31st of March (that is, two days later) I had infor- 

 mation from another locahty in Kent, of some " lice " heing 

 found on *' Grape " Hoiis. Early in April, Mr. Whitehead 

 further wrote me that he had found more "lice" on Hop 

 shoots, and that two farmers had just called and brought 

 more, and on the 12th of April Dr. T. A. Chapman, writing 

 from Hereford, reported that after careful search in the Hop- 

 yards where the bine was two feet high, he could find no 

 trace of'Jiij,'' but on the following day he found a bine with 

 seven or eight aphides on it. These were wingless and nearly 

 full-sized. 



Also in the Stoke Edith experiments, made in 1884, it was 

 found that in the case of the Hop-hills which w^ere dressed 

 with applications to keep the aphides from coming up from 

 around the Hop plant, the bines on these hills (more than 

 twelve hundred in number) were free from attack until the fly 

 came at the end of May, although the rest of the Hop-ycird ivas 

 infested. 



We do not know the reason of this at present, but it may 

 at least be conjectured that it is owing to some amount of 

 hybernation of the aphis in female or egg state in the 

 Hop-hill. 



Peevention and Remedy. — Measures for lessening presence 

 of this attack on Plum are similar to those for remedy of 

 Aphis yruni mentioned at p. 147, in its summer form as a 

 broadscale attack in Hop fields, the treatment is not wholly 

 applicable to orchard and garden use. 



Observation. — Myzus mahaleh, Fonsc. — In Bulletin No. 7, 

 New Series, of the United States Department of Agriculture, 

 Division of Entomology, pp. 52-59, is an able paper by Prof. 

 Theodore Pergande, with life-history and carefully detailed 

 descriptions of this migratory species of Plum plant-louse as 

 observed by the wa-iter, and considered, so far as he has been 

 able to ascertain from his personal investigations made near 

 Washington, U.S.A., in 1886 and 1887, to be identical wath 

 the species known under the various synonyms of Aphis 

 mahaleh, Koch, JMyzus mahaleh, Passerini, Phorodon humidi 

 var. malaheb, Buckton, and others unnecessary to specify here. 



The great point (from an economic point of view) of Prof. 

 Pergande's observation is the circumstance that, "whereas 

 Phorodon Jmmuli subsists as far as is known exclusively on 

 different varieties of Plum and Hop," migrating from the 

 Plum in spring to the Hop, and return migrants in autumn 

 leaving the Hop and supplying the Plum with a new infesta- 



