436 



SCIENCE OF GARDENING. 



Part II. 



2274. Ofivorms (class Vermes, L.), there are only a few genera which are materially in- 

 jurious in gardens, the earth-worm (Lumbricus), the slug (Limax), and the snail (Helix). 



2215. The slug (Li?nax) is without a shell, and distinguished by its lateral pore. There are 16 British 

 species : the L. ater [fig. 412. b), alba, and hyalinus are the most common in gardens ; and the L. agrestis 

 (a) is common both in gardens and fields, and is the species recommended to be swallowed by consumptive 

 persons. The snail {Helix) is a numerous genus, and, like the slug, very destructive to plants and fruit : 

 both snails and slugs are hermaphrodite, having both sexes united in each individual ; they lay their eggs 

 with great care in the earth, and the young ones are hatched, the slugs without shells, and the snails 

 with shells completely fonned. They are most troublesome in spring and autumn, and during mild 

 weather in winter. In dry warm weather, and during frosts, they retire into the earth and remain there 

 in a torpid state. The most common species is the H. hortensis (Jig. 412. c), or garden-snail, of which it is 



412 



remarked, that having once attacked a leaf or fruit, it will not begin on another till the first is wholly 

 eaten. Snails, slugs, and worms, may be annoyed by caustic substances scattered over them, or by water- 

 ing with bitter infusions, acids or alkalis, as vinegar, or what is equally effectual and cheaper, lime-water ; 

 but the only effectual way of getting rid of snails in gardens is by hand-picking. They may be collected 

 under decaying leaves or haulm, laid down on purpose to attract them. In this way a garden may soon, 

 and at little trouble and expense, be effectually cleared of the worm class of enemies. 



Suesect. 2. Operations for subduing Vermin. 



2276. The operations for deterring the human, quadruped, and feathered enemies of 

 gardens are few, and have been already noticed. (2220. 2222, 2223.) 



2277. Tlie operations for destroying insect vermin, or counteracting their injurious 

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



2278. 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 at- 

 tended to, it will seldom happen that any species of insect will exist in gardens to an injurious degree. 

 But some parts of culture, such as climate, are often beyond our control ; as, for example, when a very dry 

 spring and east winds prevail, 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 pro- 

 portion as the plants on which they 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 gardener 

 cannot apply good culture to plants in the open air, and therefore cannot prevent the increase of insects. 

 In artificial plant-habitations of every kind, however, properly constructed, his power in regard to culture 

 te complete, and therefore he may always prevent, not the existence, but the injurious increase of insects. 



2279. The palliative operations are various. Artificial bad weather will annoy every description of organised 

 being, and especially animals. Excessive waterings, stormy applications of water with a syringe, violent 

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

 wind ; these and similar operations will materially injure and annoy insects, both in their common func- 

 tions and in the work of generation, hatching, and rearing. Insects may be farther annoyed by throwing on 

 them acrid waters or powders, as tobacco- water, lime-water, powdered quick-lime, soot, ashes, barley-awns, 

 &c. &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 they are 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 the shreds, in preference to the leaves of the plant. The effect of the fumes of tobacco, sulphur, 

 urine, See. 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 degree hardened ; and water at 200 degrees or upwards 

 may be poured over leafless plants. There are various other ways in which insects may be annoyed, and 

 often in part destroyed, which will be pointed out in treating of the plants which particular species 

 inhabit. The effects of insects may also be palliated on one species of plant, by presenting to them 

 another which they prefer : thus wasps are said to prefer carrots, the berries of the yew, and the honey 

 of the hoya, to grapes ; honey or sugared water to ripe fruit, and so on. One insect or animal may also 

 be set to eat another, as ducks for slugs and worms, turkeys for the same purpose, and caterpillars, and 

 ants for aphides, and so on. 



2230. The operations for the utter removal or destruction of insects are few, and chiefly that of hand- 

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

 by 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. It is no small proof of the advantages of a 

 knowledge of natural history to gardeners, and also of the progress of knowledge among this ingenious 

 and useful class of artisans, that a practical gardener has actually practised for several years the catching 

 of moths, to prevent them from laying their eggs on his trees. P. Musgrove, gardener, at May-field near 



