to curl up and afford them protection to a much greater 

 extent than those of the Green Aphis, while those of the Oat 

 Aphis cause no curling whatever. By June or July a change 

 in the life-history of all three species takes place, and winged 

 forms are produced, which nevertheless are all females and 

 all viviparous. These winged forms in the case of the Eosy 

 and Green Apple Aphides now fly off to other food plants 

 for the rest of the summer. In the case of the Eosy Aphis 

 the alternate food-plant is said, in America and Canada, to 

 be different kinds of plantain (Plantago spp.), but this does 

 not appear to be the case in Britain. Where they really fly 

 to has not yet been traced; but they have been found on the 

 guelder rose (Viburnum opulus). The Green Aphis is not 

 normally a migrant. It can and does alternate between the 

 apple and the thistle (Carduus), but such a migration is un- 

 usual, and it normally continues its activities upon the apple. 

 The third species, the Oat Aphis, migrates regularly during 

 the first half of June to such plants as cultivated and wild 

 oats, barley, wheat, and different grasses. Late in September 

 and during October the migrants return to the apple and pear 

 nnd produce a generation of oviparous or egg-laying wingless 

 females, and in the case of the Green Aphis wingless males. 

 In the Eosy and Oat Aphides winged males are normally 

 produced before the return migration takes place, and fly 

 back to the apple later than the migrating females. The 

 generation of wingless females produced on the return of 

 the migrants to the apple are fertilised By the males, and 

 before the winter arrives lay their eggs, thus completing the 

 cycle. 



Natural Enemies. Aphides have several natural enemies. 

 None appear, however, to check them much until most of 

 the damage has been done. These natural enemies are (1) 

 parasitic insects, (2) predaceous insects, and (3) fungoid 

 enemies. The parasitic enemies are small Hymenopterous 

 insects, called C-halcid Flies; the predaceous are Lady Bird 

 Beetles and their larvae or Coccinellida; the Aphis Lions or 

 larvae of the Lace Wing Flies (Chrysopidtz) ; the Slug or 

 Leech-like larvae of the Hover Flies (Syrphidce) ; and the 

 maggots of certain Gall Midges (Cecidomyiida). The latter 

 seem to be most abundant in North Britain. None of these, 

 however, appear to be of any practical help on a large scale, 

 and no reliance can be placed on them as a means of check- 

 ing " Aphis Blights." 



The fungoid enemies, of which there appear to be many, 

 also appear too late to stop any epidemic, and when they 

 attack late colonies, that is, after all the damage has been 

 done, a few Plant Lice escape, enough to produce under 

 favourable circumstances a blight in the following seasons. 



