7° 4 



GA RDENERS' MA GA ZINE. 



October 29, 1898. 



APHIDES. 



The season of 1898 has witnessed an unusually widespread attack of aphides, or 

 " green flies," as they are commonly called, upon trees, plants, and flowers of 

 many kinds. (Aphides are termed M green flies " indiscriminately, as if they were 

 of the same species, though each kind of tree, plant, and flower has its peculiar 

 species, with as well-defined distinctions as the host upon which it is found.) It 

 is believed that the mildness of the winter and the absence of sharp frosts preserved 

 the hibernating aphides of species that are generally affected by normal winter 

 weather ; while the abnormally small rainfall also favoured, without doubt, the 



preservation of these species. 



The Board of Trade Journal states that among the trees most seriously attacked 

 by aphides were limes and beeches. The foliage of the former trees, in some 

 cases, shone with the honeydew falling from the numbers of aphides on the under 

 surfaces of the leaves ; their fragrant blossoms were materially lessened by the 

 injurious action of the insects ; and many of the leaves withered and fell prema- 

 turely. Varieties of ornamental limes in gardens and shrubberies, such as Tilia 

 argentea, T. europea, and T. euchlora* suffered particularly from the continuous ac- 

 tion of aphides in the past season. The aphis infesting limes is known as Pterocallis 

 HIub % of the family Lachnince, whose wingless viviparous female is yellowish-green 

 with a black head, and a long and narrow^ body with black stripes upon the 

 abdomen. The winged female is yellow with dark legs, and ample iridescent 

 wings with forked cubital veins. Boussingault states thac in Switzerland these 

 aphides often kill lime trees by their persistent attacks. 



The beech aphis (Pkyllapkis fagi) belongs to another genus of the Lachnitiu. 

 It seriously injures the common beech (Fagus sylvestris) t as well as the u Copper " 

 or Purple beech. There were many complaints of harm caused by aphides to 

 Purple beech trees in gardens and shrubberies. The insects swarmed on the 

 under sides of the leaves and changed their rich glossy colour to dull sombre tints. 

 This aphis covers itself with a waxy exudation resembling white cotton or silk, 

 which with the " honeydew" forms a nasty, sticky mass on the lower parts of the 

 leaves. The wingless viviparous female is green when deprived of its cottony 

 coat, with a rather narrow body, large red eyes, and a short beak or rostrum. 



With regard to remedial measures against these aphides infesting trees, it is 

 impossible to adopt any in the case of fully-developed and large trees. Young 

 trees and fair-sized trees in gardens, public parks, and in shrubberies may be 

 syringed with soft soap and quassia by means of specially constructed garden 

 engines, having strong pumps. In several instances purple beeches were syringed 

 in this way with very great advantage. The mixture used was 7 lbs. of quassia 

 chips and 7 lhs. of soft soap to 100 gallons of water. 



Peach and Nectarine Aphis. 



Peach and nectarine trees were infested with the aphis named Aphis amygdalu 

 As the fungus Exoasrus deformans, causing what is termed the " curl," was 

 abundantly present in many gardens, this aphis was not always held to be the 

 author of much harm, though, in fact, it did incredible mischief to the trees as well 

 as to the crop of the present year. Spraying and syringing with soft soap and 

 quassia, in the proportions of 6 lbs. of soft soap and 6 lbs. of quassia chips to 100 

 gallons of water, was successfully adopted in the case of this insect. Spraying, 

 too, with a weak solution of sulphate of copper and lime, at the rate o* 5 lbs. of 

 sulphate of copper and 2^ lbs. of lime to 100 gallons of water, was useful against 

 the M curl " fungus. 



Plum and Hop Aphis. 



The " blight," as the attack of aphides is termed in Kent, sorely beset the hop 

 plants. There has seldom been such a persistent visitation. As fast as the hop 

 growers washed off the insects fresh swarms appeared, and, where spraying or 

 " washing," as it is called in the hop districts, was neglected, the leaves turned 

 black, and the cones were black and full of filth. The :hop aphis (Phorodon 

 humuh) is distinguishable by the lowest joint of the antennae being toothed, and each 

 of the frontal tubercles is also furnished with a tooth. A remarkable feature in 

 the life history of this aphis is that it migrates from trees of the Prttnus tribe to 

 the hop plants in the spring, returning to the former to lay eggs upon them, in 

 which state the winter is passed. Clouds of winged aphides may be seen in 

 September leaving the hop grounds on their way to the plum, damson, and sloe 

 trees in the neighbourhood, and, in the spring, flights of winged females are again 

 seen coming from the plum and damson trees. It was long ago believed that there 

 was a migration of these aphides from plum and damson trees to the hop plants, 

 a So Pro ^ ssor . RlIe y determined this by close observation made near Maidstone in 

 1887. There is little doubt that besides the hibernation of this insect in egg form 

 upon trees of the Prunus tribe there are some wingless viviparous females, which 

 hibernate m the ground close to the hop hills, if the weather is not abnormally 

 severe, and produce young upon the first approach of spring. In many hop dis- 

 tricts, notaHy in Kent, where there are numbers of damson trees, and where the 

 plantation of these trees is gradually extending, aphis blight regularly recurs, and 

 with increased intensity, entailing enormous expense in washing the plants, which 

 operation frequently has to be done five and even eight times. 



But this hop aphis— which comes from plum and damson trees in the spring 

 and returns to them in the winter, when eggs, to be seen easily with a pocket lens, 

 are laid on the twigs and branches— must not be confounded with the plum aphis 

 \Aphis pruni). This insect remains upon plum and damson trees throughout the 

 year, and is quite a distinct species from t^e hop aphis. It makes its appearance 

 in the form of wingless females, popularly known as green lice, the products of 

 eggs laid in the autumn. These bring forth living young, which again give birth 

 to lice and multiply in a remarkable manner, there being, according to Westwood, 

 nine generations. In seasons of bad attacks, notably in the last (1898), by the 

 time the damsons are formed they are beset by aphides which suck up the juices 

 from the stems and the leaves near them, and cause them to drop off, or to be 

 stunted and misshapen. Plum trees are also often seriously injured in the same 

 manner, but not so much as the damson trees. As a rule, prudent fruit growers 



spray or wash damson and plum trees, before the fruit is formed, with solu- 

 ^a°iL S r S ° a r P and q uassia ' mad e of the extract of 6 or 7 lbs. of quassia chips 



w., vi™ % - £Ga ? l V°° gallons of wate '- This solution, thoroughly applied, 



ItKwr™ the paS ^ 8Cason in cleaning off the aphides and their filth. 



to £ m^ mixed with the quassia and soft soap solutions, makes 



pu^oi four ° n 7 n ^ SmaU W***Y of Pa " S is USed f ° r this 



Th e Apple Aphis. 



is of coiW^ makes its appearance as soon as the leaves show 



signs 

 ment. 

 leaves 



the blossoms, which are sweet, and either prevents fructification n 

 tiny fruitlets that, weakened by the extraction of their iuices tWrf° ks the 

 properly. Those that manage to set rarely attain to full size and oerfiS! " SCt " 

 the leaves of the trees come out they are covered with aphides and rnVi „ u As 

 black, and finally fall. H ana curl U P> become 



The winged viviparous female has a light green body with hk V 

 ings, and wings with peculiar neurations. The egg-laying female. £1 mark " 

 what round in shape, they deposit Httle black eggs between the folds J onhe^rind 



j j — ' 4 . r V ul r . ~ -oucKton, irom which are 



produced many generations of lighter green larvae, the main cause of the activ 

 injury to the leaves and blossoms. These larvae have long rostra, or suckers anH 

 are covered with fine white powder. It is considered that in some cases ' and 

 when the winter season is mild, wingless viviparous lame hibernate as in the cl 

 of the hop aphis. Washing or spraying apple trees is of great benefit if it is 

 done early and well. It not only clears away aphides, but at the sam° time 

 materially checks the winter moth and other allied caterpillars, as well as th 

 apple sucker (Psylla ma//) and the apple weevil (Anthonomus pomorumY The 

 materials used for spraying apple trees are the extract of 6 lbs. or 7 lbs. of quassia 

 chips and 6 lbs. or 7 lbs. of soft soap to 100 gallons of water. Paris green added 

 to this in the proportion of 4 oz. to 100 gallons of the mixture is of great advan- 

 tage, as it poisons the food of the insects and does not hurt the foliage or blossoms. 



The multiplication of pests like the apple aphis and of other insects is much 

 influenced by the neglected and unpruned condition of the apple trees. Where 

 the bark is thick and full of deep fissures, and the branches are thickly twisted 

 together, and when lichens and mosses are allowed to cluster densely upon the boughs 

 and twigs, insects are generally far more numerous and destructive than upon trees 

 that have been pruned properly, well scraped, and cleared from foreign growths. 

 The lamentably neglected condition of many of the apple orchards of this country 

 serves to intensify and to perpetuate the visitations and injuries of the apple aphis, 

 the woolly aphis, the whole tribe of winter moths, the ermine moth, the apple 

 blossom weevil, the Psylla, the codlin moth, and other pests, to say nothing about 

 equally dangerous fungi. Other insects also depend upon these neglected apple 

 trees for their subsistence, or make them their shelter and refuge, from which they 

 emerge to blight or destroy other crops. 



Currant Aphis. 



Among aphides which were particularly abundant and troublesome to black 

 and red currants during the past season was the Rhopalosiphum ribis, the currant 

 aphis, which makes galls, or swellings, upon the surfaces of the leaves of black or 

 red currant bushes. The galls are usually of a red colour, and upon examination 

 of the under surfaces it will be seen that there are companies of larvae engaged 

 in sucking up with their club-shaped syphons the juices from the leaves, causing 

 them to blister, curl up, and eventually fall. The currants in these circumstances 

 often " shank" and u run off," like grapes in vineries where the conditions are 

 unhealthy. The winged viviparous female has large, long translucent wings, 

 and is prettily marked, having a yellow body with black and green bars and 

 spots, a black thorax, and yellow legs with black feet. At the end of the season 

 wingless egg-laying females are evolved which lay long large eggs, and fasten them 

 to the stems and twigs of the currant bushes. In this aphis, which is green in 

 colour, the wingless viviparous female, or adult wingless female, has large cauda 

 projecting beyond the cornicles. 



Cherry Aphis. 



Myzus cerasi is another aphis infesting currant bushes as well as cherry 

 trees, but there are several and important differences between this and 

 Rhopalosiphum ribis. The wingless female is much broader and has a some- 

 what squat form, being dark in colour with yellow legs, and the winged females 

 body is also much broader with different venation of the wings. 



This inject does not make galls upon the leaves, but the swarms of larvce con- 

 gregate under the leaves and suck out their juices. They also emit quantities of 

 the curious secretion known as honeydew, which falls upon the leaves below 

 them, also upon the bunches of fruit, CDvering them with sticky filth. The other 

 currant aphis, Rhopalosiphum ribis, does not emit honeydew. 



The action of Myzus cerasi upon cherry trees is the same as upon currant 

 bushes. The leaves are pierced by countless beaks, or rostra, and the fruit is 

 covered with honeydew. 



It is almost impossible to use remedial measures for the attacks of these insects 

 upon currant bushes. The leafage is so thick that spraying is a most difficult 

 operation, and could hardly be performed so as to reach the aphides upon the 

 leaves within the bush, especially in the case of red currant bushes. It might be 

 attempted early in the season, when the aphides are first discovered and the leaves 

 not so dense. After infestation black currant and red currant bushes should be 

 pruned more closely than usual. The cuttings should be taken away and burned. 

 Spraying with kerosene emulsion might be tried, before the leaves appear, upon 

 bushes infested in the previous season, as it might make the surroundings o! tne 

 aphides unpl j asant for them when they come on the scene. 



Cherry trees fastened to walls may be easily sprayed, and small standards also, 

 either with garden engines or knapsack machines. Large trees would require 

 special machines with powerful pumps. The quassia and soft soap mixture, as 

 presc-ibed above, would be the best to use. Spraying should be done early 

 soon as aphides are seen. 



Aphides on Vegetable Crops. 



Carrots and parsnips were much infested by an aphis, the former being injure 

 somewhat seriously in various market garden districts and in allotment and P n 

 gardens. The leaves of many of the plants became quite shrivelled, ana wm 

 were consequently stunted and deformed. The mischief was generally noi h 

 so great in the case of parsnips, though in a few instances the roots were 7 



* from the exhaustion of the leaves by ;he aphides. 



115 



poor and u spindly 



Celery 

 The species 



plants were also infested by the same aphis and somewhat injured, lhc P\ 

 of aphis found upon the carrots and parsnips was that ^^Jj^J^ 

 pastinacex. The winged viviparous female is yellowish green with a oar**, 

 head and yellow legs. The wingless female is green, with long ; vasito m 

 nicies. The legs and the antenna are short ; the rostrum is f^f^^S 

 shaped towards the end, and finally terminates in a sharp, turn to 



very young the larvce are often of a light brownish hue, but they soon 



green 



full of 



It is obviously difficult to spray carrots and parsnips, as they are djffi 

 foliage, and the leaves of carrots are often close to the ground. It . i n c 

 cult to spray celery plants if a knapsack machine is used, and it tm i is 

 with quassia and soft soap, in which a little paraffin is mixed, cn the 

 together, it would also keep off the celery fly, a far greater pest uhm. 



^ardlv out Jk-T u x, blossor n of certain kinds of apple trees whose 

 appears hefni li, i blossom is formed— as a rule, the blossom of 



re the leav « are perfectly developed. The aphis attacks 



