1909.] The Insect and Allied Pests of the Hop. 619 



(green lice), and they commence to produce more pale young, 

 and so on until September, or even early October in some 

 late seasons. In the meanwhile winged broods may now 

 and again occur on the hop and fly off to other hops and set 

 up a fresh area of attack. 



In September and October a winged brood (return- 

 migrants) fly back from the hops to the damsons,- &c. Great 

 numbers of these get caught up on oak, apple, and various 

 other trees, and die. Those that reach their proper food 

 plant produce living young, from which in October a gene- 

 ration of males and females are formed. The males are 

 winged, and the egg-laying females are wingless. Accord- 

 ing to Riley, the first generation on the prunes is sexed. 

 This is not the usual case, according to my observations, 

 although it does happen. Males may either arise on the 

 prunes or fly from the hops later than the return female 

 migrants, which have produced the wingless oviparous 

 females. Then these females deposit the sexually-produced 

 eggs. Riley found eggs on prunes as early as October 1st. 

 I have never found any as early as this. The main attack 

 of Aphis on hops undoubtedly comes from the damsons, &c. 



Natural enemies of the hop-damson Aphis are not many, 

 and have little or no effect in checking this pest. Amongst 

 the most important are the Ladybird Beetles, or Cocci- 

 nellidce (PI. VI., Fig. 2). Both adult beetles and their larvae, 

 or so-called "niggers," feed upon the young and mature 

 Aphides. The larvae of the Lace-wing Flies (C 'hry sop idee) , 

 or Golden-eye Flies, as they are called in Kent gardens, are 

 also often to be found ravenously eating the "dolphins." 

 Their curious stalked eggs (PL VI., Fig. 3B) are very notice- 

 able. 



Hover Flies {Syrphidce) (PL VI., Fig. 1), which feed on 

 plant-lice generally, in their leech-like larval stage, seldom 

 occur amongst hops, and very few Hop Aphides ;ire para- 

 sitised by Chalcids and other parasitic hymenoptefa. 

 Ormerod records a Harvest Mite, one of the Trombidiidce, 

 as attacking the Hop Aphis. It was not identified, and does 

 not appear to have been observed since 1885. 



Treatment and Prevention. — As long as there are wild 

 prunes in the hedgerows, so long shall we have a certain 



x x 2 



