INSECTS. 



of our most useful plants which is not assailed ' 

 in some way or other; and the forms of in- 

 sects, and their modes of living, are so infi- 

 nitely diversified as to enable them to continue 

 their depredations in all the different states of 

 these plants. The various dnds of grain, for 

 example, have a host of enemies in the sub- 

 terraneous larvce of beetles which consume 

 the roots; various kinds of caterpillars feed 

 on the blade ; some particular species attack 

 the ear; and even whe laid up in apparent 

 security, a small beetle is often found to scoop , 

 out the interior of each grain, and convert it 

 into an abode for itself. (See CORV WEEVIL.) 

 In England, if the seed of the turnip escape 

 the attack of a minute weevil, another enemy 

 awaits the unfolding of the cotyledon leaves, j 

 and a third buries itself in the bulb and root- ; 

 lets, which become diseased and covered with 

 unseemly excrescences (see AXBURT), while 

 the mature foliage is often consumed by cater- 

 pillars. 



"But even when there is no remarkable 

 augmentation of their numbers, there is rea- 

 son to believe that the injury occasioned to 

 vegetation by insects is at all times greater 

 than is generally supposed. Their operations 

 an- often carried on under cover, either be- 

 neath the surface of the soil, within the sub- 

 stance of the plant, or in other situations 

 where they escape observation. Many kinds 

 again feed only during the night, and conceal 

 themselves during the day in holes and cre- 

 vices. In consequence of this latent and in- 

 sidious mode of attack, there is no doubt that 

 we are often led to ascribe the unhealthiness 

 and decay of plants to badness of soil, unfa- 

 vourable weather, and other causes, when in 

 reality they are produced entirely by insects." 

 ((}i'nrf. Jmn-n. Jlgr. vol. viii. p. 97.) "The only 

 tJorirse," adds Mr. Duncan, " which is likely to 

 lead to the discovery of proper remedies, is to 

 investigate carefully the habits and natural 

 history of insects in connection with the struc- 

 ture and general physiology of the plants 

 which they attack. In prosecuting this object, 

 the attention should be directed to ascertain 

 the time when, and the manner in which, the 

 eggs are deposited, as well as their composi- 

 tion, and that of the enclosing membrane, with 

 a view to determine in what way the vital 

 principle might be most easily destroyed. The 

 habits of the larvae call for particular atten- 

 tion, as it is generally in this state that the 

 mischief is committed; the period of their ap- 

 pearance, their times of feeding, plants on 

 which they feed, and (if attached to more than 

 one) the kind they seem to prefer, the part of 

 the plant attacked, duration of the larvae state, 

 should be carefully noted; an acquaintance 

 with the places to which the larvae usually re- 

 treat when about to change to pupa?, and with 

 the structure, duration, &c. of the latter, might 

 probably suggest some easy means of destroy- 

 ing many in that dormant state. A knowledge 

 of the economy of the perfect insect is of 

 coarse of the utmost importance ; if we could 

 becorr.e acquainted with the retreats in which 

 they pass the winter, or find means to destroy 

 the few that generally survive, when they first 

 appear in the spring, and before they have de- 



INSECTS. 



posited their eggs, the injuries which are sus- 

 tained by their means might be altogether pre- 

 vented." (Ibid. p. 99.) 



Let not, however, the farmer, when he is thus 

 warmly engaging in the destruction of the an- 

 noying insects of the field, omit to consider 

 whether many of these are not, in some shape 

 or other, productive of benefit whether they 

 do not serve to keep within reasonable limits 

 other insects, or perhaps perform some other 

 wise purpose in the works of the creation. 

 This has been proved to be the fact in the case 

 of the common earth-worm, whose casts so 

 often annoy the gardener and the farmer. (See 

 E \RTH- WORM.) For these not only assist in 

 the continual admixture of different strata of 

 earths, but, by boring the soil, they promote in 

 it the circulation of the atmospheric gases, and 

 even the drainage from it of its superfluous 

 moisture. And as White, of Selborne, remarks 

 in his Natural History, "The most insignificant 

 insects and reptiles are of much more conse- 

 quence, and have much more influence in the 

 economy of nature, than the incurious are 

 aware of. From their minuteness, which ren- 

 ders them less an object of attention, from their 

 numbers and fecundity, earth-worms, though in 

 appearance a small and despicable link in the 

 chain of nature, yet, if lost, would make a 

 lamentable chasm." 



Insects have been divided by entomologists 

 into two great divisions the winged and the 



\Vi nued insects are divided into the follow- 

 ing orders : 



1. Coleoptera. Of this order are the weevils, 

 the rose-bug, ground and dung beetles, &c. 



2. Orthoptern. Of this order are the cock- 

 roach, field cricket, grasshopper, &c. 



3. Hetnipterti. Of which are the field, tree, 

 and bed-bugs, fetid bugs, &c. 



4. Neuroptera. In which are comprehended 

 the dragon fly, lace fly, ephemera, &c. 



5. Hymenoptern. In this order are bees, 

 wasps, ants, saw-flies, gall-flies, &c. 



6. Lepidoptera. Of which order are the but- 

 terflies, moths, &c. 



7. Rhipiptera. Of which are certain minute 

 insect parasites living on bees, wasps, &c. 



8. Diptera. Of this order are gnats, house 

 flies, musketoes, ox and horse flies, &c. 



The insects without wings (Aptera) are di- 

 vided into the following orders : 



9. Myriapoda. Of this are the centipede, 

 lulus, &c. 



10. Thysanura. Including small, soft, leaping 

 insects, generally covered with a silvery down, 

 and found in damp places, under logs, &c. 



11. Parasita. The lice tribe, &c. 



12. Suctona. The flea. 



I. The Transformation of Insects. Insects 

 commonly change their form several times in 

 the most apparently magic manner. A few, 

 the Aphis, for instance, are viviparous, but 

 they are generally produced from eggs, that is, 

 the eggs are produced in the body of the mo- 

 ther. "The female," says Kollar, "lays her 

 eggs (which are often stuck on and covered 

 with a kind of glue to protect them from the 

 weather) shortly after pairing, instinctively in 

 the place best adapted for their developement, 



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