July 17, 186G. } 



JOURNAL OK HORTICULTURE AND COTTAGE GARDENER. 



43 



a dozen have been replaood by trees of leas sizo roraovod in 

 June, and these, though not in pots, havo not appeared to 

 suffer in tho least. However, being small they afford no 

 parallel to largo specimens, although they confirm in a cortain 

 degree tho view taken in my former article, that March is, 

 perhaps, the worst time for transplanting tho Welliugtonia. 

 —J. R.] 



RED SPEDER. 



Red sriDEn is, perhaps, the most destructive at all the in- 

 sects which tho horticulturist has to combat. TJeing small, 

 and confining its first attacks to the under side of the leaves, 

 it is not easy of recognition in its early stages of development ; 

 but in a very short time foliage attacked by it assumes a sickly, 

 yollowish appearanco on tho upper surfnco, and the parts im- 

 mediately over the spots where the insect is at work become 

 dotted with a number of minute whitish specks if tho leaves 

 aro those of the Peach or Fig tree, but if they are those of the 

 Vine the specks are of a yellowish hue. These specks or dots 

 increase ill size until the whole leaf acquires a yellow and 

 mature appearance, and its powers of exhalation and inhala- 

 tion being destroyed it falls off. The small specks or dots on 

 the upper surface of the leaves are the best evidence of the 

 presence of red spider, and if the under side of such leaves 

 he examined there will be observed between the principal 

 nerves a number of minute specks or dots. These, on being 

 touched with the point of a pin, will be seen to move about at 

 a rapid rate, and if observed with the aid of a lens they will 

 be found to be in constant motion, busy on that part of the 

 leaf which they have for greater security enveloped in a net- 

 work of the finest threads conceivable. If measures be not 

 taken to check the spread of the insect on its first appearance 

 it will rapidly wrap the leaf in a fine network, and will not 

 cease its work of destruction until the juices of the leaf have 

 been so completely exhausted that it becomes totally incapable 

 ol performing any of its functions, and falls off. 



It is well to remember that the leaf of a Vine or other plant 

 may have every appearance of being attacked by red spider, 

 and yet that the insect may not be present ; for the upper sur- 

 face of a partly scorched leaf has much the same aspect as 

 ■one suffering from red spider, but instead of specks or dots, 

 scorched leaves usually exhibit blotches ; besides, in addition 

 to the dots on the upper surface, there are others correspond- 

 ing to them on the under surface, and when there are both, 

 and those on the under side move when touched, it is certain 

 that the leaves are not scorched, but infested with red spider. 



Though the insect is termed the red spider, scarcely one 

 npon a leaf will be found of that colour, most of them being 

 of a grey, inclining to a reddish brown, and having whitish 

 heads and legs. The colour and size of the insects vary in 

 the case of different plants, for on some they are much brighter 

 in colour and larger than on others. 



The red spider attacks a great variety of plants, but chiefly 

 those which have large glossy leaves and require a largo supply 

 of water ; and yet it does not exclusively confine itself to the 

 smooth-leaved plants, but is as partial to the Egg-plaut as to 

 the Violet or Strawberry. It appears to be constant in nothing 

 but in showing the same tokens of its presence, and in this 

 respect it varies but slightly, if at all. Not being an entomo- 

 logist, I must leave a full description of the insect to those 

 more qualified for the task ; and here I may observe that a text- 

 book on insects injurious to garden crops, published at a mode- 

 rate price, would be a boou to many, who, like myself, are 

 willing to learn and yet cannot obtain a work on the subject, 

 ■except at a cost totally disproportionate to their means. 



Of red spider I am only acquainted with two kinds, or species. 

 1st, The small and very active one that attacks Vines, Melons, 

 and most cultivated plants grown under glass or in warm situ- 

 ations out-doors. 2nd, A comparatively large one, which I 

 have only found on the Gooseberry and Ivy. I have known 

 .the latter attack Gooseberry bushes with such severity as to 

 make them look as if they had been scorched. This is very 

 commonly the case on light gravelly soils. 



Red spider destroys the vitality of the leaves, checks growth, 

 and when its attacks are severe altogether arrests it. It pre- 

 vents the flowers expanding or attaining their perfection, as 

 well as the swelling and maturation of the fruit, and impairs 

 the well-doing of the plant. It likewise, by stopping growth, 

 limits the action of the roots, converting a vigorous plant 

 into one which is sickly. 



Tredisposing causes innumerable have been assigned for it3 



attacks, but tho principal appear to be a dry atmosphero and 

 a high temperuturo, with too little air at night. Some enter- 

 tain tho opinion that no plant would bo attacked by insects if 

 it were healthy ; but I have not yet seen a plant, however 

 healthy to all appearance, that did not become infested with 

 some insect. The green aphis is equally partial to a strong 

 shoot of the Rose as to a weak, drawn shoot of the Pelargo- 

 nium, and it is tho samo with most insects ; come they do, 

 and whatever they attack is checked in growth, and more or 

 less reduced in health, vigour, and fertility. In whatever state 

 a plant may be attacked, whether weak or strong, the effects 

 are the same; it becomes impaired in health and vigour, and 

 when freed from insects it regains both. Surely this does not 

 show that constitutional ill health and impaired vigour are 

 essentials to insect attacks. I believe that they are not induced 

 so much by any peculiar condition of the plant as by the at- 

 mosphere being favourable to the development and increase 

 of the insects. Mako a plant as unhealthy as we may, it will 

 not be attacked by the insect peculiar to it until we also pro- 

 duce an atmosphere favourable to that insect. 



That the red spider delights in and is encouraged by a dry 

 atmosphere none having experience of it will doubt, and it is 

 most abundant where the heat in houses is artificially derived 

 from flues Qr hot-water pipes. I can also affirm, from many 

 years' daily observations, that where there is a plentiful supply 

 of atmospheric moisture, a temperature from fire or natural 

 heat no more than tho plant requires, and thorough ventilation, 

 that the attacks of red spider are not grievous. Any one- 

 having experience in forcing Vines, Melons, &c, knows how 

 much more liable to the attacks of red spider are the crops 

 obtained by employing great artificial heat than those to which 

 less artificial heat and more air are given ; nor can those who 

 wash or syringe their Peach trees have failed to find how free 

 of red spider such trees are, whilst others not syringed are 

 literally eaten up if dry weather prevail. A dry atmosphere, 

 too high a temperature, especially at night, and insufficient 

 ventilation, are the conditions under which red spider presents 

 itself; but there are cases in which it will appear when none 

 of the conditions favourable to its existence are present. Still, 

 the fact of the insect existing may be taken as evidence that 

 the air is too dry, too hot, or imperfectly ventilated. 



The great agent in the destruction of red spider is water, 

 which may not inaptly be termed its natural enemy. TVater 

 forcibly driven against foliage infested with red spider will free 

 it of the pest, and that is the best means to adopt in the case 

 of plants which will not be injured by its application ; syring- 

 ing with soft water is the best remedy as well as preventive 

 which I have tried. Whenever a plant shows unmistakeable 

 signs of the presence of red spider, it is well to syringe it 

 forcibly, directing the water against the under side of the 

 leaves, and this is best done in the evening at the time o£ 

 shutting up the house, or, if the house is not closed, or the 

 plants are exposed, after the sun has declined in power. Bear 

 in mind that syringing once or twice is not of any great avail, 

 but it must be persisted in until the trees are cleared. The 

 only cases in which the use of water for the destruction of red 

 spider cannot be recommended, are when the trees or plants 

 are in flower, for then a dry atmosphere may be desirable for 

 the setting of the fruit, and when a tree is ripening its fruit 

 or wood then a free use of the syringe may not be advisable. 

 When syringing can be adopted it will be found the very best 

 means for the prevention and destruction of insect enemies. 

 It is conducive to health and vigour, frees the leaves of dust, 

 and lessens the evils of an artificial or dry atmosphere. It is 

 objected to syringing that it is not natural, and cannot be 

 otherwise than injurious, it being sufficient if the atmosphere 

 be kept moist by sprinkling the floors, walls, &c, and by the 

 evaporation of water from troughs upon the hot-water pipes. 

 Such may be the case, but I have failed to experience it, having 

 seen tho foliage of the Vine brown and ready to fall off by the 

 time the fruit was ripe, and Peaches shedding their leaves 

 before the wood was mature. 



When the syringe cannot be used, then we must look else- 

 where for the means of destroying the red spider; and here I 

 would discriminate between plants which can, and others which 

 cannot, bear an application destructive to the insect. I may 

 instance the Vine and Melon as plants to which a solution 

 of soft soap at tho rate of 2 ozs. to the gallon cannot be safely 

 applied, and yet soft-soap water of this strength is effectual, 

 and not injurious to the foliage of most trees and plants, when 

 applied with a syringe so as to thoroughly wet every leaf on 

 both sjdes. Three applications on alternate evenings will be 



