Book VII. NOXIOUS WORM TRIBES. i^^ 



fowl and wiUl-fowl wliich it attracts, as it forms the favorite food of their young. The fecundity of the 

 common gnat (C. pipiem, fig. 1G3 fc) is as remarkable as that of the flesh-fly. 



6910. The tabanus genus greatly resembles musca, and produces some species troublesome to men and 

 other animals, on whose blood they feed. The spider-fly {Hippobosca) inhabits woods. The species known 

 as the forest-Jfy (//. equina, fig. 7631) is particularly tormenting to the horse. 



SuBSECT. 8. Of AjHerous Insects. 

 6911. The aptera, or insects without wings in both sexes, is composed of genera of 

 such varied forms, that no other general characters can be affixed. Linnceus compre- 

 hended in this order spiders, lice, lobsters, crabs, shrimps, &c. which Leach and most 

 other modern naturalists class separately. 



6912. The louse {Pcdiculus) and fiea (Pulex) are well known : the only genera of this order which are 

 troublesome to the cultivator are the mite- spider (Acarus), the common spider (Aranea), and the wood- 

 louse {Oniscus.) 



6913. Tlie red spider is the Acarus tellurius, L. [fig. 764 a), and 

 the same name is also applied by gardeners to the scarlet acarus 

 {A. holosericens, L. 6), the only two British species of the genus 

 which infest plants, and to which perhaps they do more injury 

 than all other insects put together. Watering over the leaves is 

 the well known preventive and remedy : the water should be 

 ap])lied to both sides of the leaf in a finely divided state, and with 

 great force, so as to dash the insects to the ground. For this 

 purpose Read's syringe is the most efficient implement at present 

 in use. The sheep-tic {A. rcduviics, c), the dog-tic {A. ricinus, d), 

 the cheese-mite (?i. giro), and the itch-mite {Mite de la gale, Fr.), 

 {A. extilcerans, L.), which inhabits the ulcers of the itch, are tha 

 principal species mentioned by Linnaeus; but some naturalists 

 consider that every animal, and most plants, have their peculiar 

 species of acarus. The harvest-bug is considered by some an 

 acarus, and by others a phalangium. 



6914. The common Sfrider (Aranea) is a numerous genus, and 

 very prolific : as they live entirely on insects, they cannot be con- 

 sidered as otherwise injurious to the cultivator than by their un- 

 sightly appearance. 



6915. The wood-louse (Oniseus), is of retired habits, shunning the light and the heat of the sun. It 

 lives on leaves, fruit, and also on animal substances, and casts its crust or skin like the spider. In general 

 it is easily caught by bundles of reeds or beans, or other hollow stalks, like the earwig. The O. aquaticus 

 (e) is common in springs and clear ponds, or cisterns of water. The dog-tic and water oniseus (/, g) 

 both require to be magnified to be studied properly. 



SuBSECT. 9. Operations for subduing Insects. 



69 1 6. The operations for destroying insect vermin, or counteracting their injurious effects, 

 are of three kinds, preventives, palliatives, and efficient processes. 



6917. The preventive operations are those of the best culture in the most extensive sense of the term, 

 including what relates to choice of seed or plant, soil, situation, and climate. If these are carefully 

 attended to, it will seldom happen that any species of insect will exist to an injurious degree. But somo 

 parts of culture, such as climate, are often beyond our control ; as, for examj)le, when a very dry spring 

 and east wind prevails, in which case many insects increase, or rather their larva; are hatched and reared 

 under such favorable circumstances that few of them die, and all of them become strong in proportion as 

 the plants on which tiiey live, in consequence of the dry weather (favorable to the insects), become weak. 

 In such a case as this, or its reverse, that of a series of cold moist weather, the agriculturist can do little 

 or nothing. 



6918. The palliative operntio7is are various. Artificial bad weather will annoy every description of or- 

 ganised being, and especially animals. Excessive waterings, stormy application of water with a syringe, 

 violent wind produced by shaking the plant or tree in tlie air instead of moving the air round the tree, as 

 in natural wind; these and similar operations will materially injure and aimoy insects, both in their 

 common functions and in the work of generation, hatching, and rearing. Insects may be farther annoyed 

 by throwing on them acrid \vaters or powders, as tobacco-water, lime-water, powdered quick-lime, soot, 

 ashes, barley-awns, &c. The smell of tar is particularly offensive to various moths and butterflies ; and it 

 is said, if a little of it is placed under plants, or if thfey arc watered with tar-water, these insects will not 

 lay their eggs on them. It is also said that if shreds of flannel are hung on trees or plants, moths and 

 butterflies will lay their eggs on tlie shreds, in preference to the leaves of the plants. The effect of the 

 fumes of tobacco, sulphur, urine, &c. are well known. Saline substances mixed with water are injurious 

 to most insects with tender skins, as the worm and slug; and hot water, where it can be applied without 

 injuring vegetation, is equally, if not more powerfully, injurious. Water heated to 120 or 130 degrees 

 will not injure plants whose leaves are fully expanded and in some degfee hardened ; and water at 200 

 degrees or upwards maybe poured over leafless plants. 



6919. The operations for the titter removal or destruction of insects are few, and chiefly thatofhand- 



Eicking, or otherwise removing or killing by manual operations with a brush, sponge, or net Destruction 

 y hand-picking should, if possible, commence with the parent insect in its fly or perfect state before it 

 has deposited its ova. Thus the gathering of moths, butterflies, and large wasps may save the gathering 

 afterwards of thousands of caterpillars and the drowning of hundreds of wasps, as preventing weeds from 

 seeding in a garden will soon eradicate them altogether. 



6920. Catching the winged insect, or hand-picking the eggs, or larvfc, are the only certain modes of pre 

 venting the ravages of the gooseberry caterpillar. As soon as the eggs, which are white, and no thicker 

 than hairs, are deposited and appear on the under side of the leaf, they should be rubbed off, or the en- 

 tim leaf gathered It is true, watering the leaves well, and then dusting them with powdered quick- 

 lime, will destroy all those eggs which are wet at the time the lime falls on them : but will it fall on the 

 under sides of the leaves ? \vlitering with lime-\vater is better ; but even that operation is less certain, 

 more troublesome, and not much more expeditious than hand-picking taken in tiino. In extreme cases, 

 both modes may be combined. 



Sect. IV. Of the Worm Tribes injurious in Agriculture. 

 6921. Of worms {Vermes, L), there are only a few genera which are materially inju- 

 rious to agriculture^ viz. the earth-worm [Lxtmbncus), the slug {Limax), and the snail 

 {Helisx). Tiie wire worm, so injurious to corn sown on soils newly broken up, and also 

 in gardens, is not a worm, but the larva; of a species of Tipulo ; commonly of 2'. crocata 

 and oleracea. (6907.) 



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