90 



IRISH GARDENING. 



blue flowers, and grows up lo eighteen inches in 

 heighth, making a fine display. 



D. Henderson! has thick, blnnt leaves and rosy 

 purple flowers on stems abont a foot high. 



Other forms occasionally met with are 

 D. eliipticum, D. alpinum, D. patulum and 

 D. frigidum. but the nomenclature is somewhat 

 confused, and it is by no means certain that the 

 plants passing nnder these names are always 

 right. B. 



Insect Pests of Fruit. 



Black Currant Mite. 



This pest is one that should be carefully studied 

 by every gardener concerned with fruit produc- 

 tion. No absolute remedy has yet been discovered 

 that will completely eradicate it from fruit planta- 

 tions when once it has gained admittance. Men 

 of science are devoting umch time to the --tudy of 

 the life history and habits of tlie Mite, and also 

 to devi.iing means for its destruction. This is a 

 work in which all can help. The practical culti- 

 vator by close observation may learn much, and 

 by experiments in the way of spraying through- 

 out the seasons as far as possible, and ))y removing 

 hit/ })U(Js in the dormant time may do much to 

 add to the sum of our knowledge concerning this 

 menace to the future of the Black Currant crop. 



The months of May and June are said to be the 

 time when the mite,^ are on the move seeking 

 new buds in which to take up their quarters. 

 Spraying at this time should be destructive of vast 

 nmni)ers. and woidd ])0-sibly, in a season or two, 

 ch-ar a plantation. Tlie right spray fluid to u.5e 

 is still a matter of experiment, but there is some 

 probability that lime-sulphur solution may be 

 efficacious owing to its adhesive properties, 

 though it is proi)erly a fungicide. Paraffin emul- 

 sion i.^ also worthy of consideration, while Quassia 

 Extract has also Ix-^n reconnnended. 



Apple Aphides. 



By Fred. V. Theobald. 

 South-Eastern Agricultural College, Wye. Kent. 



The so-called " Aphis " or "Blue Bug" blight 

 of Apples, and to a minor extent of Pears, is in 

 some years one of the worst ills fruit-growers and 

 gardeners have to contend with in this country.^ 

 The terms Aphis, Dolphin or Blue Bug "blight" 

 are couunon names in all fruit-growing districts. 

 They apply to dauuige done by several species of 

 plant lice or anliides. 



Out of the eight species of aphides recorded as 

 attacking the Apple in Great Britain only four are 

 of general imi>ortance. These are : (i) the Blue 

 Bug or Kosy Apple Aphis (Aphis mnJ'ifoVuf'. 

 Fitch); fii) the Green Apple Aphis {Ai>hh pomi. 

 Be Geer); (iii.) the Oat Anple Aphis (S}}>]iocnry7ir 

 avemxi, Fabr.), and the Woolly Aphis or American 

 Blight (Hchizoncura lanidrra, Hausmann). 



The following article deals only with the first 

 three, which are leaf, blosi5om, shoot or fruit 

 feeders, unlike the Woolly Aphis, which feeds on 

 the wood and roots as a rule, but which in very 

 bad attacks may spread also to the leaves and 

 fruit. This latter insect is dealt with in the 

 Board's Leaflet No. 34. By far the greatest 

 amount of harm is done by the Aphis maHfoli;i\ 

 but in some years and in certain localities the 

 Green Apple Aijhis (Apliis pomi) and th('()at 

 Apple Aphis {Hiphdcorync urcnsp) are of I'onsider- 



al)le importance. The life histories of many 

 Aphides are now well known. A definite annual 

 migration may take place between two totally 

 different host plant>', as is seen in the case of 

 the Hop Aphis (Fhorodon liumidi), which annu- 

 ally migrates from the hop, to winter on the Sloe 

 and Damson, in the egg stage, and in the various 

 '■ gall-forming " Poplar Aphides (Thecabius 

 (ifpnis, &c.). which leave the Poplars in summer 

 and fiy to such plants as I{<tniinriihis, Gnnphn- 

 lium, &c., and then Imck to winter on the poplars 

 in the egg stage. 



On the other hand there are many kinds which 

 a]>i)arently have erratic and local migratory 

 habits. The Apple Aphides — ApJiis mnIifoH;i\ 

 Apliis jxnni. and the Woolly Aphis {Srhizuneura 

 Idnigrrd) come in this group, at least as far as 

 the w^riter has been able to trace in this country. 



The more salient features of most destructive 

 plant lice on fruit are known, and as such alter- 

 nate host plants as damsons sloes, plantains, &c., 

 cannot be exterminated, the matter is more of 

 scientific than of practical importance. 



l)umu{)p. Caused hy Apple Aphides. — The dam- 

 age occasioned by the three species of Apple pest^ 

 mentioned below is mainly to the foliage and 

 young wood, but al.>o to some extent to the fruit, 

 which they stunt and deform; wdiilst one, the Oat 

 Aj)ple Ax)his (Siphoeorynr arenre), may damage 

 the blossom as well as the leaves; and in some 

 seasons similar damage is done by the Blue Bug 

 or Ro.-y Apple Aphis (.4. mdlifoJiiv). The Green 

 A])ple Aphis (.4. pdrni) mainly attacks the young 

 idioots, and so densely do the insects cluster, on 

 them that they cheek the growth. They do not, 

 however, produce such distortion as is caused by 

 A. nidUfntin'. The laist-named, by means of the 

 constant puncturing of the leaves by its proboscis, 

 causes these to curl up, and beneath this shelter 

 the lice reproduce, in certain seasons, at a great 

 rate. The foliage becomes r<mothered and 

 poisoned by their honey-dew and other excretions 

 and turns brown; in some cases the lice produce, 

 earlier in the year, yellow or rosy-red galled 

 masses on the leaves. Later they may swarm on 

 the leaf-stalkr-, shoots and fruitlets, and V)y their 

 l)unctures deform them. The leaves may fall and 

 only a few stunted and galled Apples remain. The 

 crop is now and then completely ruined by this 

 pest and the trees have a serious set back for the 

 next season and probably for a longer time. 



The Green Apple Aphi.^ (.4. pomi) may on 

 occasions produce a certain amount of leaf-curl, 

 ])iit never to the same disastrous extent as is 

 caused by .4. m<difo]i:r. Moreover, it never 

 occurs in such vast numbers. Tt imiinly feeds 

 upon the young top growthi?, and although pro- 

 ducing but little deformed growth, it nevertheless 

 checks the health of the tree, especially when on 

 young stock. 



The Oat Apple Aphis {H. aveiur) does little 

 liarm as a rule, except where it invades the 

 l)lossom trusses, in which case the writer has very 

 often seen appreciable damage done. Tt produces 

 little or no leaf curling, appears earlier, and 

 matures and flies away much sooner than the 

 other two kinds. 



A lijii'iiid nic (if flir Species. — 



(d) Alate or Winged Viviparous Fe.male.«; : — 



1. .4. mdlifoJiir. — Cornicles black, rather 



long. Abdomen red and black. 



2. A. pomi. — Corniclo^ black. r;ither long. 



Abdomen green with black lateral spots. 



