70 



In the first section of the 



TROMBIDIIN.E 



Fig. 55. 



we find the genus Tetranychus, to which the "red spider" (Tetranychus telarius) belongs. 

 This is a serious pest to gardeners, and one which all those 

 who have to do with plants under glass are more or less 

 familiar with. Fig. 55 represents the male of this species, 

 very much enlarged, the mite itself being scarcely visible to 

 the unaided eye. (The small dot within the circle at the 

 side of the figure indicates the natural size.) The characteristics 

 of this genus of mites seem to show a special affinity with the 

 spiders, in their habit of spinning webs, for which purpose the 

 claws of their feet are specially adapted. The mouth has a 

 barbed sucking apparatus, by which the sap is sucked from 

 the minute vessels in the leaves of the plants they attack. 

 These mites vary very considerably in colour, influenced much 

 in this respect by the food they devour ; some are greenish 

 and marked with brown specks on the sides, others are rust- 

 coloured, or reddish, or even brick-red, the latter being the 

 colour with which horticulturists are most familiar. It is 

 probable that most of the individuals acquire more or less of 

 a reddish hue, when fully mature. 



This mite spins a web on the under side of the leaves, of the finest and most delicate 

 texture, the threads being so slender, that one fails to see them, even with the help of a 

 magnifying glass, until after they are woven into a web or net-work. The threads are 

 secreted from a conical protuberance situated underneath and near the extremity of the 

 abdomen, and they are drawn out and guided by the motions of the insect, and by the 

 action of the minute claws of the feet. In constructing the web the feet are moved 

 quickly, and the threads are attached to the hairs and other prominences of the leaf, and 

 under this shelter will be found a colony, consisting of many mature individuals of both 

 sexes, and young mites of all ages, which feed and multiply rapidly. By the aid of their 

 jaws, which are not unlike the beak of a bird, they tear away the surface of the leaf, and 

 then plunge their beaked suckers into the wound and suck the juice. 



The eggs of this mite are nearly round, colourless, and large in proportion to the size 

 of the insect. The larva is a minute transparent object, not unlike its parent, but it has 

 only six legs and creeps slowly. The leaves of the plants attacked soon indicate the pre- 

 sence of this invader by their sickly hue, the sap being sucked by myriads of tiny mouths 

 the leaves are deprived of their natural nourishment, and soon assume a yellowish cast, 

 with patches of a grayish or lighter shade, the under surface becomes whitish, and ft the 

 the mite is allowed to pursue its course unchecked, the gardener soon finds his cherished 

 flowers and shrubs much injured or destroyed. 



This insect is said to pass the winter under stones, concealing themselves there when 

 the leaves they have fed on have fallen. 



The remedies used for such enemies as the red spider are various preparations of 

 sulphur and soap, used separately or together, mixed with water, and applied to the plants 

 with a syringe. Sulphur in any form seems useful ; laying it in the form of powder upon the 

 pipes in the greenhouse has been recommended. Plain soap and water is said to be 

 effectual, indeed water alone freely used is regarded by some as sufficient ; it is well known 

 that the insect thrives best in a dry atmosphere. In applying these liquids, to insure 

 success it is necessary that it be used so as to wet the under side of the leaves, if applied 

 to the upper surface only, the mites may remain attached to the lower side with perfect 

 security during the entire operation. The gardener is aided in his war against this pest 

 by other mites and insects which prey upon them. The larvae of the lace-wing flies, 

 and other friendly insects, are said to devour large numbers of them. 



There are a number of other species belonging to the genus Tetranychus which injure 

 plants and trees. The cucumber, the rose, the cyclamen, the vine, have each a different 



