208 THE CANADIAN ENTOMOLOGIST 



aphis is very marked, for the leaves become deformed in a blister- 

 like manner, the damaged areas being coloured a rosy or pallid 

 yellow tint. This appearance, to some extent, resembles that 

 caused by Aphis cratagi Kalt. I first noticed this in the Marden 

 area in Kent in 1907, and in recent years in my own garden on 

 an old Cyder Apple. Ants were found carrying the aphides down 

 this large tree to some espaliers below, viz.. Lord Sut^eld, Peas- 

 good, Bramley Seedling and Cox's, but the effect caused l)y the 

 aphides on them was quite normal. This shows that under certain 

 conditions and on certain varieties the effect of this aphis varies. 

 Walker records A. sorhi as appearing in thick clusters on Sorhus 

 domesticus near London in 1847, giving the leaves autumnal red 

 and yellow tints; this record again may refer to true sorhi. In 

 some years in Britain Aphis ^of/;M does enormous harm — perhaps 

 1915 has been the worst year of all. Many orchards were quite 

 ruined by it, the foliage scorched, and in very many the fruit 

 badly deformed by the pimctures of the aphides, and consequently 

 of no commercial value. In one plantation \isited, which had 

 been banded with Tanglefoot, but not sprayed, the insects swarmed 

 all over the trunks and the bands were completely covered with 

 thick layers of them. Some were found crawling up, others down 

 the trees, all being aptera? or nympha'. On July 4th this wandering 

 ceased, and the majority commenced to become winged, many of 

 the alata? died on the trees, many others flew away. 



Variation in colour. — I know of no aphid which varies so much 

 in colour in the apterous stage. In one district they may all be  

 slaty-grey, in another all bluish black, and locally called the "Blue 

 Bug," in others most are plum cclour or brown, but all have a 

 small sprinkling of pale reddish or pink forms with them and called 

 the Rosy Aphis; now and again this alone occurs. In some cases 

 I have found colonies a dull brown, very similar to Koch's figure 

 of his Aphis Pyri. 



Natural Enemies in Britain. 



Towards the end of June a few Coccinellidcc, many Syrphid 

 larva? and now and then a Chrysopid larva may be found 

 feeding on this insect. By the first week in July they become 

 more abundant, and by the second week, as a rule, these "natural 

 checks" seem to have obtained the ascendency over the "Dolphins." 



