876 



INSECT. 



Taking into consideration the immense number of 

 species of insects, which, as we have already ob- 

 served, so far exceed all the other animal sub- 

 kingdotns; it must, however, be evident, as Mr. Mac 

 Leay observes, that it is here, owing to their myriads 

 of species, that the mode in which Nature's chain is 

 linked a mode, the knowledge of which comprises 

 all knowledge in natural history will be most evi- 

 dent, and therefore most easily detected. This same 

 circumstance also is attended with another conse- 

 quence. If the species of insects (and, indeed, of 

 any tribe of animals) be so numerous, and their 

 natural distribution so difficult of attainment ; and 

 yet, nevertheless, if we would retain and extend the 

 knowledge which we already possess, either of their 

 structure or habits, it must be evident that this can 

 only be done by distributing their groups in the most 

 convenient mode for reference. This may, and, 

 indeed, must be done in an artificial method ; that is, 

 we select certain constant characters which may, never- 

 theless, possess but very little influence upon the 

 habits of the animal, and which, indeed, in many 

 cases, compel us to separate groups which we know 

 to be naturally allied by affinity with each other. 

 Thus we separate the wasps from the bees, because 

 the former fold their upper wings longitudinally 

 when not flying; and thus we divide the beetles 

 according to the joints of the tarsi, although in some 

 instances direct affinities are thereby separated. 



Nevertheless, the great advantages resulting from 

 an artitical method are so obvious, that we find them 

 admitted by persons who do not hesitate to reject, 

 as an absurd i'ancy, the existence of a natural system. 

 These advantages will appear the more evident when 

 we investigate the actual number of insect species. 

 Our great and pious naturalist, John Ray (" le pre- 

 mier veritable naturaliste pour le resrne animal," as 

 the equally great Cuvier has styled him), in his 

 " Wisdom of God," published at the close of the seven- 

 teenth century, tells us respecting the number of 

 British insects : ' The butterflies and beetles are 

 such numerous tribes, that I believe in our own native 

 country alone, the species of each kind may amount 

 to loO or more. The fly kind (if under that name, 

 we comprehend all the flying insects, as well such as 

 have four, as such as have but two winffs, of both 

 which kinds there are many subordinate genera), will 

 be found in multitudes of species to equal, if not ex- 

 ceed, both the forementioned kinds. The creeping 

 insects that never come to be winged, though for 

 numbers they may fall short of the flying or winged, 

 yet they are also very numerous. Supposing then 

 there be a thousand several sorts of insects in this 

 island and the sea near it ; if the same proportion 

 holds between the insects natives of England and 

 those of the rest of the world, as doth between plants 

 domestic and exotic (that is, as I guess near decuple), 

 the species of insects on the whole earth (land and 

 water) will amount to 10,000, and I do believe they 

 rather exceed than fall short of this sum." Subse- 

 quently, however, in consequence of having discovered 

 a greater number of English moths and butterflies 

 he was induced to consider that the total number of 



tish insects might be about 2000, and those of the 

 whole earth 20,000. Mr. Stephens, however, in the 



st perfect catalogue of insects ever yet published 

 devoted to the British species, has introduced not 

 fewer than 10,000 native species, and perhaps 2000 

 or 3000 remain unnoticed. 



Linnaeus, in the edition of 1761, of the Fauna of 

 Sweden, described 1700 species; and in the twelfth 

 edition of the Systema Naturae, the entire number of 

 these animals (Swedish and exotic), with which he 

 had become acquainted, amounted to about 3000; 

 but during the last half century the investigation of 

 insects has so much progressed, that Mr. Mac Leay, 

 in his Horse Entomological, published in 1821, stated 

 that there were certainly more than 100,000 of the 

 annulose animals (nearly synonymous with the Lin- 

 naean insects), preserved in the various collections. 

 The latest insect census is, however, that of Dr. 

 Burmeister, who states that there are in Germany 

 about 6000 plants (including Cryptogamid), and more 

 than 12,000 insects; so that, if this proportion be 

 constant, the number of known insects, according to 

 the 60 70,000 known plants, will amount to 120 

 140,000 species; and if the opinion of the latest 

 botanists be adopted, that about one-third of the col- 

 lective species of plants are known, the number 

 of species nhabiting the earth would amount to 

 360420,000 species. Kirby and Spence, indeed, 

 averaged six species of insects to one phaneroga- 

 mous plant, and considering there may be 100,000 

 species of phanerogamous plants in the world, they 

 obtain the number of 600,000, or more probably 

 400,000 species of insects. There are computed to 

 be 28,000 species of beetles in the royal collection at 

 Berlin ; and from the supposed superiority of the 

 extent of the coleopterous order, Dr. Burmeister 

 considers that the actually known species of insects 

 may be thus distributed : 



Coleoptera . . . 36,000 

 Lepidoptera . . 12,000 



Hymenoptera . . 12,000 

 Di'ptera '. . . 10,000 

 Hemiptera . . . 4,000 

 Other insects . . 4,000 

 Mr. Stephens's British catalogue shows the follow- 

 ing proportions ; but it must be observed, that the 

 attention lately bestowed upon the minute Hymeno- 

 ptera and Diptcra, have raised their numbers very 

 considerably : 



Coleoptera . . . 3300 



Lepidoptera . . . 1838 



Hymenoptera . . 2054 



Diptera . . .1671 



Hemiptera . . . 605 



Other insects . . . 544 



Now it must be evident, that unless some convenient 



and easily applicable mode of classifying these vast 



masses be adopted, the mind will be compelled to 



remain in a state of the most profound darkness. We 



will not, however, dwell upon this subject, but refer 



our readers to the article CLASSIFICATION. 



The annulose, or insect sub-kingdom, is divisible 

 into the four classes above mentioned ; viz., Crus- 

 tacea, Arachnida, Ametabola, and Ptilota, or winged 

 insects ; which last Mr. Mac Leay separates into 

 two distinct classes, as mentioned in our observations 

 on the mouth of insects; namely, Mandibulata and 

 Haustellata. These classes are again divisible into 

 orders. 



Linnaeus adopted the structure of the wings as 

 affording the characters of his orders, which were as 

 follows : 



I. Coleoptera. Wings four, the upper pair qrus- 

 taceous with a straight suture (beetles and 

 earwigs). 



