Page:Popular Science Monthly Volume 14.djvu/519

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varies with the plant on which it is found, and in different individuals on the same plant; a rusty color shows maturity. This mite, like most of the genus, spins a web on the back of the leaves so delicate that a single strand can not be seen even with the aid of a common magnifier. When the web-work is done, however, it is plainly visible,

PSM V14 D519 Trombidium and tetranychus telarius.jpg
Fig. 2.—Trombidium parasiticum.
Fig. 1.—Tetranychus telarius—perfect insect, male. Fig. 3.—Trombidium sericeum.

and under it the mites congregate in numbers, and feed and multiply very fast. The leaves soon look sickly, are marbled with gray and yellow above, the underside being white and shiny, with recurved edges. A microscope will show hundreds of mites of all ages, together with unhatched eggs pasted to the web; they are draining the leaf-vessels of their sap, and choking the breathing-pores with excrement. The remedies used to get rid of them are various, but sulphur seems the most potent of them all. It is recommended to lay flowers of sulphur on the heating-pipes in the hot-house, or it may be mixed with soapsuds, and applied to the leaves. Plain soap and water is effectual if made to reach the insect, but a bent syringe or some other means must be employed to reach the underside of the leaves, otherwise the mites will remain in comfort and safety through a hard drenching. Luckily for the florist, they are preyed upon by other mites and insects—the grub or larvæ devouring whole colonies of them very quickly. The cucumber, cacti, vine, etc., as well as the shrubs and herbage of wood and field, support various species of this genus; they are all of similar habits while confined to vegetation, and to be got rid of by similar methods. But some of them transfer themselves to the skin with seeming ease, and when thus lodged cause great discomfort, producing itching and redness, and sometimes eruptions similar to those of the itch. Two species known in the Mississippi Valley as jiggers are very annoying to those who have to expose themselves where they