88 



GARDENERS' MAGAZINE. 



February 



female is reddish -yellow and very small, seldom larger than "003 of an inch. 

 There are males also produced in the autumn (also arostrate), these fertilise the 

 oviparous females, which deposit a single ovum each in crevices of the bark of the 

 apple trees, so as to ensure the continuity of the species. The existence of a 

 winged viviparous female was doubted by Hausmans and Knapp, whilst Lichten- 

 stein observed them swarming in the orchards of Southern France. Buckler 

 received some from the latter authority in September, 1878, from Montpellier, and 

 since then numerous notices of them have appeared in Kent and elsewhere in 

 England, and also in America. 



The Probable Origin and Present Distribution. 



The name " American Blight" is given to it on account of its supposed origin 

 in that continent. This is strongly protested against by Dr. Asa Fitch. It was 

 known in Europe in 1787, and was said by Serville and Amyot to have been 

 imported from England to the Continent. Its origin in England, according to 

 Sir Joseph Banks, was near London, in a nursery which was partly stocked from 

 America. The first serious loss from this pest was in the vicinity of the 

 metropolis. Gradually it spread into the western counties, where by 18 10 it was 

 sufficiently abundant to ruin the cider crop in Gloucestershire. Every year it 

 spreid further and further over England, until it is now found in nearly every 

 apple district. I have been unable to detect it except very occasionally in Wales. 

 In 18 1 8 it was doing damage around Paris, and by 1822 it was very common in 

 the departments of the Somme, Aisne, and Seine. In Germany there are records 

 of it in 1801, and in Belgium in 1812. In Italy it is still scarce. American 

 orchards now teem with it, especially in those districts with a cool climate, 

 notably the New England States. New Zealand, the Cape, and Australia are 

 also infested to a serious extent in places, especially the former colony. There is 

 little doubt but that they were derived in the latter places from England in 

 imported stock. 



Does S. lanigera have a Subterranean Generation? 



This is a question about which much diversity of opinion exists. We know 

 that lanigera, as pointed out by Buckton, often attacks the stem of the tree low 

 down and close to the ground. These are exactly similar forms to those we 

 find on the branches and twigs, and cannot be considered a subterranean race. It 

 is, however, stated on such good authority as Goureau, Saunders, Riley, and 

 Thomas, that there is a subterranean form of lanigera upon apple roots, just in 

 the same way as we see in the vine phylloxera. Buckton had not observed this 

 in England, but says, "There seems no good reason to doubt that it does exist 

 occasionally." I have made repeated inquiries and searches for this ground form, 

 and have never been able to detect it. Yet very often white, woolly patches and 

 galled swellings may be found on apple roots. In all cases the culprits I examined 

 have proved to be S. fodiens, now and again, Pemphigus lactucae. The former 

 I have found abundantly on several occasions forming swellings and white nidi on 

 and around apple roots and rootlets. Lactucae makes similar white nidi in the 

 ground, especially in winter and spring, at the roots of lettuce and various plants. 

 I have never seen this aphis forming galls, but have taken it on apple rootlets. 

 Several samples of fodiens have reached me, with notes regarding the supposed 

 American blight attack on the root*. In breeding the same the winged genera- 

 tions soon dispelled this notion. I can only add that all the cases notified to me 

 in England of this root attack have been caused by one or other of the two aphides 

 named. I at first thought the apterous lice sent me might be a ground form of 

 lanigera, and was not convinced to the contrary until the winged generations came 



above ground. • 



S. fodiens (Buckton) may be identified by the following features : The apterous 

 female is globular and shiny, yellowish and mealy, head dark brown ; antennae 

 bluish-brown, finely ringed and cupped as in lanigera ; eyes absent— no cornicles, 

 legs bluish brown. The pupa has eyes and is redcfcsh-brown, with short dark 

 rostrum. The winged female has a slaty-grey abdomen ; head, thorax, and legs 

 shining black ; wings fuscous, coarsely punctured ; stigma yellow ; cubital vein 

 once forked and not united with cubitus.; two oblique veins to hind wings. 

 Numbers of this species live together in nests in the ground, lining them with 

 white fluffy cotton. The young larvae that arise from the winged females are 

 vermiform. Buckton thinks these are the sexual forms; they appear in the 

 autumn. Ruckton states that he has taken this species plentifully in November 

 on black currant roots at Ilaslemere from four to six inches underground. That 

 this species and probably P. lactucae occasion severe loss in apple trees cannot be 

 doubted. Many cases of apples failing have been traced to woolly lice on the 

 roots, and in all cases examined by myself, whether in the earth surrounding the 

 roots or in " galled v roots themselves, only the two species here mentioned have 

 so far occurred. Possibly subterranean American blight forms do similar damans, 

 for we cannot doubt their existence abroad when such competent observers state 

 they know the attack well, but I think in England we want further evidence of 

 its existence. This is a point of some economic importance, for if there is a 

 migration, as sometimes stated, from trunk to root and vice versa, we might check 

 to some extent their ravages. 



Natural Enemies. 



Although aphides have generally many natural enemies amongst members of 

 their own class, little good is done by them in regard to lanigera. Possibly the 

 woolly excretions and globules with which the American blight is surrounded may 

 keep these useful parasites and carnivorous foes off. I have seen, nevertheless, 

 the larva: of the Coccinellidae, or lady birds, devouring them and their wool 

 ravenously, and have known some badly infested trees cleared by them. 

 During .the present year I had a tree cleared by placing forty "niggers,' 1 as the 

 larval lady birds are called, upon it, in less than a week, cleared far more thoroughly 

 than by any insecticide. Larv.e of several species of Syrphidas, or hover 

 Hies, also sometimes feed upon them, but not to the extent that they do upon other 

 aphides. Only once have I seen them in any number amongst the *oolly aphis. 

 The lace wing flies (Ilemerobida) may also devour them, whilst the Ichneu- 

 mon^ now ami again pirasitise them to ^small extent. I have also found a 



IZfJXT™ T a ° f f the g enus Pi P iza ^ding on the root species. Riley also 

 records I^ipira radicum feeding on the ground American Blight in America. I have 

 ^seen various spiders and Phalangid* devouring them, and a species of 

 Nemacons, one of the hemiptera-heteroptera. 



Amongst birds the Blue Tit (/W cam/ens) is far the most beneficial in 

 Zund l*£ ed K )y *.* ° ne Can sec these ^ creatures hunting 



Xlelle w£tt ,n t f e M? and CleariD S ° ff this n ° xious ins ^ 

 wnoie^aie. Withou. these -feathered friends" we should suffer much more 



f uTo/ch^ the y should be strenuous^ protect^ iTaH 



with some in,J r^LlT T T^ t/f * b " ds > °/. are already infested 



in £cuciai uuxi^imj — ..T & " , t T7 v ~ auuum oe remed 



quickly and as far as possible. I he lichens and moss should be scraped 

 burnt off during the winter with the following wash : Ten pounds of caustic 



as 



or 



been found active on the trees during some of the sharpest frosts w k 

 experienced in these islands. we *Uvt 



Prevention and Remedies. 



K This blight is especially to be seen in badly kept orchards, where the tre 

 set close together, the trunks and boughs covered with moss and lichens andl** 

 in general unhealthy surroundings.^ Needless to say these should be remefod^ 



off 



ten pounds of caustic potash, to one hundred gallons of water. Not raly^ahV 

 destroy the lichens and moss, but also the lice and insects, and also most of th 

 ova laid in and upon the vegetable growth on the trees and their bark. A tr 

 washed during the winter in such a way will soon appear quite noticeable amon^ 

 the rest, it becoming quite black, and the rind and bark perfectly clean art 

 healthy and in nowise damaged by the burning action of the wash. In manyc^ 

 scraping the bark has to be resorted to, so as to get off all the rough and loo* 

 bark, beneath which the insects go in cold weather. It is also essential to clean 

 off this superfluous bark to obtain a smooth surface, so that the whitewash for the 

 trunks will take evenly. With regards to painting the trees, any thick wash with 

 a base of soft soap will be serviceable. Perhaps the following is as good as any 

 One pound of soft soap, one gallon of lime, a small quantity of size, mixed with 

 sufficient warm water to form a thick whitewash. Simple soft soap and warm 

 water is sufficient, however, rubbed over the trunks with a scrubbing brush. We 

 must remember that it is the soft soap that destroys the aphides in the various 

 washes employed by blocking up the spiracles ; the other ingredients may improve 

 the wash, but they are quite unessential as far as all plant lice may go. 



In whitewashing the trees great care should be taken to go right down to the 

 ground, as it is not at all unusual to find the blight congregated as low down as 

 the surface. In destroying them during the summer and when they are on the 

 young wood, washing to be effectual should be commenced directly the first traces of 

 the white wool appear. Prior to using the soft-soap wash, the trees attacked 

 should be well drenched with plain cold water sent with some force amongst the 

 blight by a garden engine. This will be found to loosen and destroy much of the 

 wool and thus expose the aphides to the deleterious effects of the soft soap after- 

 wards, otherwise the soft soap holds to the wool and does not touch the insects. 

 The effect of thunder showers and heavy rains is most marked upon this blight, 

 clearing it off far more successfully than any artificial washings. As much as 

 sixteen pounds of soap to the hundred gallons of water should be used as long as 

 one finds the machine does not " block." 



With regard to the attack of S. fodiens and possibly S. lanigera on the roots, 

 more difficulty in dealing with the pests will be found. One point should claim 

 every fruit grower's attention, and that is to examine the roots of all young stock 

 that comes from the nurseries. Any traces of the galled patches or white wool 

 upon the roots would soon be seen by a casual observation. The examination should 

 nevertheless be very complete, as one female may soon establish a colony. Should 

 any be found, steps should be taken to destroy it before the trees are planted, a 

 thus save much further annoyance. This can be easily done by dipping the root! 

 into warm water and strong soft-soap for a minute or two, and moving then 

 about so as the whole comes in contact with the wash, and so destroying the 

 subterranean pests. A certain amount of good may be done by exposing the 

 roots in trees that are not flourishing, and if any sign of this blight is upon them 

 a good drenching of soapsuds, so as to soak all the soil and the crevices of the 

 roots, as recommended by Dr. Asa Fitch, would be advisable. Miss Ormerod, 

 in her valuable work on injurious insects, states that the draining of stables has 

 been recommended and " is said to cure the evil." 



The introduction of " Blight-proof" stocks, such as the Majetin and Northern 

 Spy, mentioned by Mr. French in his " Report on the Injurious Insects of 

 Victoria," and by Mr. Lounsbury in this year's Cape of Good Hope report, would 

 doubtless be beneficial as far as the ground attack goes. Of course the graft' 

 would be just as liable to attack. Of course if there is a migration of S. lanion 

 between the trunk and roots, which is probable, when we find statements to that 

 effect by Miss Ormerod, Mr. Whitehead, and numerous American authority 

 bands of tarred hay or cloth around the trees, placed close to the ground, would 

 stop the migration. But it is well first to find out if those root forms are \ 

 lanigera, or the species recorded here and elsewhere. Various other s"^? 

 have been mentioned as destroying this blight, such as tobacco leaves boiled a 

 water— one pound of tobacco to six gallons of water; kerosene and paraftn 

 emulsions, and various patent insecticides, but none are successful unless soft soflf 

 is included in the wash, and that alone is sufficient, hence none of these vario 

 insecticides have been mentioned. If desired the regular proportion of qua* 

 may be added to lend its cleansing effects to the leafage, &c. The protection a 

 the natural enemies mentioned should also be paid attention to, and everj 

 encouragement given for their increase. 



,1 



Cell Growth —In a recent lecture Professor Ray Lankester considered J 

 evidences of the activity called life in the protoplasm of the cell. This, he ^^V^ 

 difficult to observe directly, but it could be inferred in various ways. Cells ^ 

 noticed in different stages of development, or they were seen to grow in SI * e * 

 divide into parts. . The enormous number of cells that built up animals ana ^ 

 had originated from other cells by division, and could be traced back to a nuc : ^ 

 corpuscle termed a fertilised germ cell. Another evidence of this vital ac ^ 

 could be found in the movements which were visible in some living ceils, a ^ 



these he mentioned the am<eboid movements exhibited by many cells ' no3 ^^ 

 animal fluids, the granule-streaming to be seen in the cells of the hairs 

 spider wort, the cyclosis of green corpuscles often visible in plant cells, the c ^ 

 turn and expansion of vacuoles, and the ciliary movements exhibited 1 ^ 

 animals by threads of protoplasm extending beyond the cell. All these ^ 

 ments of protoplasm were probably to be regarded as due to chemical cnan„ • ^ g 

 lecturer proceeded to make some further remarks about the structu r ^ 

 typical cell. After describing the Linin and Chromatin threads and rerer ^ 

 nuceolus, he discussed the function of the nucleus. This was at first th< ? u t> e n 



~. 6 .v«w uiipuuoHLc, men it was discredited, uui ui i«*ic ycaio » — ^ 



be recognised as a very important part of the cell. That such was we r^fi 



been proved by cutting into pieces some of the larger unicellular am ^ 



which could be manipulated under the microscope. If one of these was ^ 



pieces in such a way that one portion contained a nucleus, while the otner 0 



it was found that, whereas the latter, though it lived for many days, so ^ 



growth and eventually died, the former recovered itself and grew to tne ^ 

 shape of the original animalcule. The experiment thus afforded evia 



the nucleus controlled the growth and nutrition of a cell. Were trier ^ 



rhp cimr^lar f^™« ~r i:r_ ±\ , . _ _.,^i«„r- 3 Thar was a » 



iiuv,icu3 tumroiiea tne growth and nutrition 01 a ecu 

 the simpler forms of life that did not possess a nucleus ? That was 

 matter. In some cases observation failed to discover a proper nucleus 



a few huH* m,n« of „,u:„u n Z t T ^ ; \ ; m some cases observation tailed to discover a propci . 



hJ nn .ff V y ?l are already infested conclusion probably was that no cells were devoid of nuclear substance, J 



has no effect upon this insect. The aphides have some low forms was ^^^^^^^ in a pulverulent condiU 



wbi<* 



