1112 PRACTICE OF AGRICULTURE. Paht III. 



Sect. II. liirds injurious to Agriculture. 



7639. Of birds, the most decidedly injurious to man are the different hawks and 

 kites, as most of the species attack and devour young poultry. 



7640. Various methods have been proposed for remedying this evil, but they evince little acquaintance 

 -with the habits of these birds. Mr. Swainson recommends that the prevalent custom, of nailing such as 

 have been killed against barn-doors or outhouses, be exchanged for the following : In such parts of the 

 country as are frequented by those birds, let two or three poles, ten or twelve feet high, be placed in the 

 farmer's poultry yard, each pole being furnished with an iron spike six or eight inches long ; pass this 

 spike through the body of a dead hawk in the direction of the back-bone : it will thus be firmly secured, 

 and give the bird an erect position ; the wings being free will be moved by every breeze, and their unna- 

 tural motion will prove the best scarecrow either for ravenous or granivorous birds, more particularly the 

 latter. Destruction by the gun is of course the most effectual. 



7641. Whether granivorous birds are more injurious than beneficial to the farmer, is 

 very questionable. 



7642. T/ie crow, rook, raven, sparrow, magpie, and starling are commonly called granivorous ; yet this 

 is an error, for they are all omnivorous, that is, feeding both upon animal and vegetable substances, and 

 more particularly upon insects. We are annually told of large crops being either wholly or partially 

 destroyed by insects of some sort or other ; but we never hear that these injuries have been occasioned by 

 birds. These complaints have certainly been more numerous of late years than formerly, and this is 

 attributed by Mr. Swainson to the destruction of small birds (as waste lands are brought into cultivation) ; 

 to the great diminution of rookeries ; and to the foolish prejudice which the generality of farmers have 

 taken up against these latter birds, which they destroy without mercy. In this instance we have been 

 less wise than our ancestors, who protected and cultivated them, and by whom they were justly considered 

 of the greatest benefit to mankind. Nature seems, indeed, to have pointed this out to us, for she has dis- 

 tributed the crow in all parts of the habitable world. Yet the farmer will enquire, " "What good can these 

 birds do me, when they come on my newly sown land, and root up the seed ?" The answer is very short. 

 The crows and rooks do not come for the express purpose of eating or destroying the seed, but for 

 devouring the insects, snails, and grubs turned up by the plough or harrow ; these are their favourite 

 food, and while so occupied, the small quantity of seed they may eat or displace is returned to the farmer 

 ten-fold by tiiat saved from the insects. Wallis, in speaking of the destruction caused by the hedgechaffer 

 or cockchaffer, says, that ' whole meadows and corn-fields were destroyed by them ;" and judiciously 

 concludes by observing, " that the many rookeries with us is the reason why we have so few of these 

 destructive insects." {Hist. qfNorthun^rland.) 



Sect. III. Insects injurious to Agriculture. 



7643. Insects, above all other animals, are by far the most injurious to the agriculturist ; 

 not only from their numbers, but from their attacking the produce of the earth in all its 

 stages of growth and maturity. We have already pointed out the advantage, not to say 

 the necessity, of a certain knowledge being acquired respecting insects, by all persons 

 engaged in agricultural pursuits. We shall now explain, in popular language, the dif- 

 ferent tribes or orders into which they are divided ; the changes they undergo ; and the 

 injuries they produce to man, and the animals and vegetables which he cultivates. 

 Numerous insects, much more destructive than those we shall enumerate, are found in 

 other climates, but from which the British agriculturist has, happily, nothing to fear, and 

 therefore need not be acquainted with. The reader will, however, find much valuable 

 information respecting them concentrated in Kirby and Spence's IiUrodiiction to Eiito- 

 mohgy, vol. i. 



SuBSECT. I . Physiology/ of Insects. 



7644. Insects are distinguished from worms (Terraes L.) by always having feet in their perfect state, 

 as the beetle, butterfly, &a Worms crawl upon their bellies and have no feet, as the eartli-worm, slug, 

 snail, &c. The generality of insects have only six feet; but some few, generally called by this name, have 

 a great many, as the wood-louse, centipede, &c. 



7645. 'Nearly all insects are oviparous ; that is, produced from an egg. These eggs are seldom found 

 singly ; they are small in size, and do not grow. The eggs of some species are hatched in a few davs, 

 while those of others remain during the winter, and the young do not come forth until the season at which 

 the leaves of the plants upon which they feed begin to expand. 



7646. The second state of the insect is called the eruca, or larva in systematic language, and is known to 

 the vulgar by various names. Caterpillars are those larvas which are exposed, and feed upon leaves and 

 plants, as the caterpillar of the common cabbage butterfly {fig. 971. a). The larva; of beetles usually live 

 in the earth, in the trunks of trees, or in the substance upon which they feed; they are generally of a 

 whitish colour, thick and clumsy in form, and are called grubs. The larva of the common cockchafer 

 (./?g- 970. b), and of the nut-beetles {fig. 970. c), are of this description ; while the name of maggots is usually 

 given to the larvae of flies, bees, ants, &c., all of which live In the same confined state as those of beetles. 

 It is in this stage of existence that insects are most voracious, and consequently most destructive to plants. 



7647. When the larva has attained to its full size, it changes into the piipa or chrysalis state. This is 

 done in different situations, according to the tribes to which they belong. The chrysalis of butterflies 

 {Jig. 971. b, e) are naked, and are either suspended or attached to trees, branches, walls, &c. Those of 

 moths are either concealed in a case like the cocoon of the silkworm, or the caterpillar undergoes its 

 change in the earth. The period in which insects remain in this state varies according to the species ; but 

 in most cases they are inactive and torpid. 



764S. The imago, or perfect insect, is produced from the chrysalis, and is the only state in which all its 

 parts and members are fully developed. The appearance and economy of perfect insects, in general, is 

 totally different from those of the larvae and pupae, and it is only in its final stage of existence that the 

 species can be ascertained. With the exception of such insects as form the A'ptera of Linn^us, all others 

 are furnished with wings, either four or two in number. Some few exceptions, however, occur to this 

 rule ; the female of the glow-worm and of some few moths are apterous, while many beetles (although 

 furnished with hard winged cases) are destitute of real wings. 



