Book VII. 



NOXIOUS INSECTS. 



110 



',C«K). The cock-roach, railed by some the black beetle (iflatta orientalis, fig. 975. c), was originally im- 

 ported from India, but is now naturalised in every tem- 

 perate part of Europe. Like most of its tribe, it shuns 

 the light, both natural and artificial. In the I-ondon 

 houses, particularly in the rooms on the giound-floor, 

 it is very abundant, and indiscriminately devours bread, 

 meat, flour, and even cl Mies. As soon as light appears 

 they all scamper off as fast as they can, and vanish in 

 an instant. It is said to be killed by devouring red 

 wafers. The young are contained in a singular horny 

 case (a), which is divided into a number of transverse 

 partitions or chambers ; it is rather flattened, and quite 

 smooth except one side, which is toothed. The larva 

 and pupa {.b) are both without wings, and generally 

 larger than the perfect insect (<*). 



7691. The house-cricket (Gryllus domesticus L.) is 

 sometimes as abundant in farm-houses as the cock-roach 

 is in those of London and other large towns : both insects 

 devour every kind of food, and are often found drowned 

 in pans of water, milk, and other fluids ; it is said they 

 will even attack stockings, or linen hung out to dry. 

 They require great warmth, and are therefore mostly 

 found in kitchens and bakehouses. Another species is 

 peculiar to pastures, which, in conjunction with the 

 male cricket, feeds only upon roots : both these, how. 

 ever, are too local in this country to be very extensively 

 injurious. 



7692. The bacon-grub (Dermc'stes lard^rius L.) is a 

 great pest to the winter provisions of the farmer, devouring hams, bacon, and all sorts of dried meats. 

 This is principally done when the insect is in its larva or grub state Jig. 970. /). When full fed it be- 

 comes a chrysalis g\ which ultimately changes into a small beetle y/i) about a third of an inch long, of a 

 dusky brown colour, with the upper half of the wing-cases whitish or ash-colcured, marked with black 

 specks. The grub, from lying concealed in the meat, cannot be effectually removed; but by watching 

 the time when the perfect insects appear, they may then be destroyed, and a recurrence of the evil in h 

 great measure prevented. 



7693. Woollen clothing of evert/ description, furs, Sjc. are liable to be devoured by the larva; or caterpillars 

 of no less than five distinct species of small moths. Most of these enclose themselves in little tubular case* 

 of a silky texture, and are so well disguised externally by fragments of the stuff' they feed upon as often to 

 escape immediate observation. The receipts for preventing these ravages are numerous, but few of them 

 can be depended upon. Asa preventive, pieces of Russia leather, or tobacco leaves, may be laid between 

 the folds of garments in drawers) which are not often used. If there is reason to fear the moths are in 

 the house, these garments should be frequently opened, and aired by exposing them to the sun. When 

 furs of anv kind are laid bv for the summer, they may either be sprinkled with snuff or camphor, and 

 Russia leather or tobacco leaves put in the drawer or box. Should the moth actually have got into furs, 

 the only wav of checking the evi! is to put them into an oven moderately heated, and by keeping them in 

 this situation a quarter of an hour every grub will be effectually killed ; the degree of heat may be ascer- 

 tained, in the first instance, bv putting in some common feathers, which should come out uninjured. 



169-1. The principal insects 'injurious to the agriculturist have now been enumerated : there are many 

 others which feed upon cultivated vegetables and domestic stores, but in a less extensive degree. Let us 

 not suppose, however, that these little animals have been created for our punishment or annoyance. We 

 have but taken a view of one side of the picture ; the other would show us innumerable benefits, either 

 immediate or remote, which we derive from this race of beings. The silkworm, the honey-bee, and the 

 cochineal insect must not be forgotten; and myriads of others are created, whose sole occupation during 

 life appears to be that of devouring and keeping within due limits those tribes that are injurious and 

 hurtful to man. 



Subsect. 6. Operations for subduing Insects. 



695 The operations for destroying insects, or counteracting their injurious effects, are various, and in 

 most cases must be regulated according to the species. These we have already pointed out in treating 

 upon the insects themselves, or of the particular plants upon which they feed. It only remains to offer 

 such general rules as are more or less applicable to all destructive insects ; these are of three kinds, pre- 

 ventives, palliatives, and efficient processes. . 



76Q6 The preventive operations are those of the best culture as relates to the choice of seed nor plant, 

 soil, situation, treatment, and climate : the four first are under the control of man, and an attention to 

 them will undoubtedly lessen the risk of injured crops ; but as regards weather, neither his foresight nor 

 care can avail anv thing. . , . . . , , 



7697 The palliative operations are numerous; and such as are eminently successful may be considered 

 as efficient ; inasmuch as it rarelv if ever happens that any insect can be exterminated, even from one 

 district : its numbers mav be diminished, but the species will still remain, although in such small num- 

 bers that its operations mav escape notice. Most insects will be injured, and in part destroyed, by artifi- 

 cial bad weather, such as 'excessive waterings, stormy application ot water with a syringe, and violent 

 wind produced bv shaking the tree or plant : many will thus be bruised, and others that are shaken to 

 the ground can be destroved. Insects mav be further injured by watering the plants upon which they 

 feed either with tobacco or lime-water, or bv scattering upon the leaves powdered quick-lime soot, ashes, 

 barlev awns &c The smell of tar is particularly offensive to all insects, and the effects produced by the 

 fumes of tobacco, sulphur, urine, &c. are well known. Hot water may be applied with much advantage. 

 Water heated to 120 or ld() degrees will not injure plants whose leaves are fully expanded, and it may be 

 increased to 200 for such as are without leaves. 



7698 Insects mat/ be destroyed in a much more effectual manner by enticement, or placing in theiryy 

 other food as a trap. The late" noble and generous Sir Joseph Banks has the merit of having recommended 

 and made known this most efficient method. It simply consists in cutting slices ot potatoes or turnips, 

 sticking them upon skewers, and then burying them near the seeds sown : the vermin will col ect upon 

 them during night, and by examining them every morning, vast numbers may'ie 'lestroyed^^ms plan 

 has 



clearing 

 cessfull 

 agrii 



threatened 

 slugs from 



tops being divided and the apples ; 

 with them, and omitting two alternately, till the whole field of eight acres was gone over, 



le d to demolish the plant Having beard that turnips had been used with success to entice the 

 cm wheat, he caused a sufficient quantity to dress eight acres to be got together j and then the 

 ii" divided and the apples sliced, he directed the pieces to be laid separately, dressing two sketches 



