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JOURNAL OF HORTIGULTDRE AND COTTAGE GARDENER. 



[ May 27, 1876. 



answer, " An insect is a creature with six or more legs," they 

 are cheeked by tha recollection of varione grabs and maggots 

 that are footless. I have heard it given as a broad definition 

 of an insect that it is an animal that can fly, walk, or run, 

 which is obviously inapplicable to all insects in their prepa- 

 ratory stages, and only suiting a proportion in the perfect or 

 imago condition. Mr. Wood alludes to a section of the com- 

 munity in whose minds there rests a belief that insects are 

 only skin and squash, but even these would scarcely give this 

 Bimple formula forth as a definition. Then as to size and 

 Bhape — these are no standards, since some insects are larger 

 than certain quadrupeds or birds ; and as to shape, there is an 

 infinite variety of this noticeable in the insect world. Bat the 

 word just used needs only to bo broken in two, and we at once 

 have a help to the right understanding of the uatare of an 

 insect. The body is divided into parts, sections, or segments, 

 more or less noticeable in different species and individuals, 

 yet always existent, and furnishing a most reliable distinction, 

 since no such formation occurs in the higher animals. I point 

 this out as immediately connected with the familiar English 

 name, but there are other distinctions sufficiently obvious, and 

 easily remembered when once pointed out, to which I shall 

 have to make reference presently. 



If I were asked, " What classes of men are by their employ- 

 ment brought into most frequent contact with the insect races ? " 

 I should have no difficulty in answering, Horticulturists and 

 agriculturists ; a necessary consequence from the fact that the 

 great majority of insects are to be found living upon or closely 

 associated with vegetable growths. Yet, speakiug generally, it 

 is not amongst these that we find a large amount of knowledge 

 ■with regard to insect appearances and insect habits. If there is 

 a familiarity that breeds contempt, as a proverb assures us 

 there is, we may discover also a familiarity that produces both 

 dislike and ignorance, contradictory as that may appear. Yet 

 in saying this, and speaking more particularly of horticulture, 

 which concerns us here, my observations are applicable rather 

 to the time that has past than to the present moment, for 

 amongst amateurs and professional gardeners we now perceive 

 a growing inclination to acquire insect lore. With some, 

 possibly with most, the moving cause is the recognition of 

 the truth that it is highly advantageous to gain at least an 

 outline knowledge of the insects that belong to the garden, 

 orchard, or plantation, viewed as friends, foes, or neutrals in 

 their relation to the work of the horticulturist. Then I am 

 also glad to record that an increasing number of entomologists 

 is being drawn from the ranks of gardeners, somi becoming 

 much interested in the curious structures and the remarkable 

 habits of these creatures, long unjustly deemed to be nothing 

 better than nature's nuisances. And the day may come when 

 such facilities for acquiring a knowledge of insects as entomo- 

 logical classes, or series of lectures specially suitable to gardeners 

 and well illustrated with living or dead specimens, may be 

 common in London and other towns. 



It is interesting to become acquainted with tlie histories of 

 particular insects, and in this Journal from various sources, 

 and occasionally of late years from the pen of the present 

 author, numerous facts have been published which it may be 

 presumed are not without their value to gardeners. But of 

 course the references to insects thus given from time to time 

 cannot be supposed to help greatly towards a methodical 

 knowledge of insects as a class of living things, though they 

 bring out prominently individual species. I have recently 

 observed that, however well such life-histories may be sketched, 

 something more is wanting to bring up tho gardener's know- 

 ledge of insects to the proper standpoint. A man msy read, 

 and even ponder carefully, much that is written upon insects, 

 and yet have very hazy notions about their grouping or classi- 

 fication. Is this an indifferent matter ? Assuredly not. Few 

 are so ignorant as not to perceive that a beetle and a moth are 

 decidedly unlike each other, and that a grasshopper and a 

 blow-fly are not next-of-kin, but they may not go much farther. 

 Whether we have as many kinds of beetles as of moths, or in 

 what respects the grasshopper's life is different from that of 

 the blow-fly, about these and a host of other particulars 

 they are in the dark. Now, it could be demonstrated that an 

 acquaintance with insects as distinguished into orders, families, 

 genera, and species, is helpful towards mental improvement ; 

 but it is more to our purpose to assert, as we may, that to the 

 horticulturist a knowledge of some of the broad distinctions is 

 highly helpful. As a general rule the habits of groups show 

 a certain identity throughout, and with an insight into the 

 general history of any one group of insectj we are the better 



prepared to understand a species belonging to that group. In 

 these pages I shall suppose myself accompanied by an intelli- 

 gent horticulturist who wishes to have, in a style not too 

 scientific, an outline sketch of the insect world so far as it 

 concerns us in these islands ; and if there should be some who 

 think I am repeating what is, or what ought to be, already 

 known to the reader, I would remind these that it is as well to 

 obviate possible difficulties at the outset. 



Let anyone who is by no means a naturalist pick up the next 

 frog he comes upon, and take a big caterpillar off the handiest 

 bush. As he looks at the somewhat incongruous pair he sees 

 differences, it is true, yet he is most likely tempted to consider 

 that they are in much closer alliance than, say, a quadruped 

 and a bird. But herein he is wrong, and stress must be laid 

 on the grand distinction between vertebrates and invertebrates. 

 In the vertebrates, running down from man to reptiles and 

 fishes, there is always found a backbone — the spinal column. 

 The skull may be wanting as in fishes, or the limbs and ribs 

 as in various reptiles, but in each class of the vertebrates there 

 is an internal skeleton on which the framework of the body ia 

 built up. An old writer, who took upon himself to unravel 

 the mysteries of Scripture natural history, saw a fancied dis- 

 tinction between the " creeping things" of Genesis and flying 

 insects. By the former term, he argued, only such insects as 

 creep, walk, or leap could be intended. Winged insects must 

 be placed under the category of " fowls of the air." But from 

 the mere possession of wings nothing can be proved as to 

 similarity, for though birds and some insects have these 

 organs of flight, they are farther apart in reality than insects 

 and molluscs or worms, which are totally incapable of aerial 

 movements. 



Insects, then, like all invertebrate animals, have no backbone, 

 and of necessity it follows that there is no central brain — ^no 

 organ to which the sensibilities, resident in the various parts 

 of the body, send " telegraphic communications," if one may so 

 speak. All the older naturalists denied insects both a nervous 

 and a circulatory system, but therein they were probably wrong. 

 In the latter circumstance they came to a hasty conclusion, 

 because on dissection they could not detect any heart nor an 

 obvious motion of fluids throughout the body. Now our best 

 authorities support the theory that a long muscular canal 

 extending from the head to the tail, and supplied with a series 

 of valves, acts as a compound heart ; from it are distributed 

 numerous minute ramifications, and through these channels, 

 as is supposed, the dorsal vessel sends through the body, and 

 receives again, a vital fluid, which we might call blood, as it 

 fulfils the same end. Mr. Newman, indeed, suggests that 

 when one caterpillar bites another, as happens occasionally 

 among the species that are inclined to be quarrelsome, the 

 flow of this greenish substance proves an incentive to rage, 

 which, were it true, would show an analogy to the recognised 

 effects of a blow drawing blood in some creatures of nobler 

 race. Then, as to nerves, " thereby hangs a tail;" connected 

 with these there lies a much- vexed and as yet unsolved question 

 — How far insects have the sensation of pain ? I am not going to 

 spill any ink in the cantroversy here, though I have been in 

 the battle-field in days gone by. Suffice it to say that insects 

 have a succession of nerve-centres or ganglions, which are 

 arranged along the body and limbs, and which seem to be 

 independent of each other. Seem ! bat there is the puzzle. If 

 they were so entirely the head of an insect might want to go 

 one way, the body in another direction, and the legs in another; 

 but somehow all the movements are brought into harmony. 

 Still, it is an odd fact that, as has been often proved, you may 

 cut an insect about strangely without causing its immediate 

 death. Then again, as to breathing, there we have the tube 

 arrangement again. On each side of the body of an insect an 

 air vessel or passage is situate, with several openings, called 

 spiracles or breathing pores, communicating with the external 

 air. The stoppage of these is death, and hence the speed with 

 which a wasp or bee may be laid prostrate by just touching the 

 abdomen with a feather dipped in oil. 



But as to general outline : If we take for examination a fly, 

 which is at the lower end of the class, or a beetle, which stands 

 at the summit ; though the one has two wings merely, and the 

 other two wings and two elytra or wing-cases, they have each six 

 legs, the almost universal number among perfect insects ; and 

 the body is divisible into the three portions, called the head, 

 thorax, and abdomen. In all insects the head is hard, aptly 

 described by one writer as a kind of box, formed of a single 

 piece, and bears the antenna in front^peculiar organs, which 

 in different species show so much variety. They are occasion- 



