10 SCIENCE PROGRESS 



in the United States and Canada, it is very common in Australia 

 and in New Zealand, and we find it in Natal and in Cape 

 Colony, as well as all over Europe, from north to south. 



The Phylloxera is another root-form which has been spread 

 artificially over the face of the earth, carrying ruin with it 

 throughout the vineyards. The Vine Louse also seems to 

 be an European insect, and has been spread to America, 

 Australia, the Cape, etc., with vine plants and cuttings. With 

 this vine pest we get, as in the Woolly Aphis, a subterranean 

 and an aerial race, and it is probably on the roots that it has been 

 distributed so widely. Every country save our own has some 

 Act or Ordinance forbidding the entry of vines, cuttings, etc., 

 from foreign countries, or else limiting the introduction in 

 certain drastic ways. 



Another European Phylloxera {Phylloxera corticalis) which 

 attacks oaks in Europe has recently been found in South Africa 

 doing considerable damage. It has doubtless been introduced 

 with seedling oaks. 



Many Aphides have been spread on fruit trees and plants. 

 One that has the widest distribution is the Black Fly of the 

 Cherry (Myzus cerast), which is now found in America, Australia, 

 New Zealand, and South Africa, as well as all over Europe. 

 The small black eggs of this aphis are not at all easy to detect 

 on young cherry trees. Thus they are easily passed unnoticed 

 with nursery stock into new areas. Living aphides may also 

 be imported from some distance. A consignment of strawberries 

 from England were examined (as all imported stock is) on 

 arrival at Durban, and all the plants were found to have many 

 living aphides upon them. Had there been no fumigating 

 regulations in vogue, a serious pest would have been introduced 

 into the colony which previously did not exist. The Apple 

 Aphides {Aphis malt, A. sorbi, and A.fitchii) common to Europe 

 and America doubtless were imported from one country to 

 another with nursery stock many years ago. 



The earth around the roots of plants must also bear its quota 

 of insect enemies, for we find the Pear Midge {Diplosis pyrivora) 

 in a few localities in America. It cannot have entered in any 

 other way. We know that the larval midges fall from the 

 fruitlets when they are mature and pupate in the soil. These 

 puparia are very small, and are easily overlooked. Mixed up 

 with particles of earth that stick to the roots, they may easily 



