Book VII. 



INSECTS. 



11 IS 



7rtf9. The duration of insects is extremely variable: the greatest proportion appear to be annua!* 

 emerging from the egg and passing through the three stages of their existence within the space of a year- 

 But there are a greaf number of species, particularly among the beetles, which pass three, and even tour, 

 years in the caterpillar state ; ant! instances are on record of beetles remaining in timber from ten to 

 fifteen years. The greatest proportion of moths are biennial, passing the winter in the chrysalis state 

 and closing their existence in the succeeding summer. The transitory life of the £p hem era is proverbial ; 

 the perfect insect indeed exists but for a day, and seems born only to continue its species ; yet in the larva 

 state it enjoys a life of one, two, or even three years. 



StiBSECT. 2. Arrangement or Cl<is$ijication of Insects* 



7650. All insects, as Macleay observes, may be divided into twogroups ; 1. Apterous insects, having either 

 no metamorphosis, or only that kind of it the tendency of which is confined to the increase of the number 

 of feet : these, as their name implies, are destitute of wings. 2. True insects, or those whose metamorphosis 

 has a tendency to give wings to the perfect or image state, but never more than six feet. 



76V>1. True insects are again divisible into two primary groups ; the first of these arc organised for mas- 

 tication in their perfect state, and the second are organised for suction alone. Each of these divisions, 

 according to the system of Macleay, contains five separate orders, the principal characters of which we shall 

 endeavour to make intelligible in common language. 



7652, The Mandibulata, or masticating insects, are furnished with jaws of a horny or membranaceous 

 substance, infinitely diversified in their form and structure. They are divided into the following orders: — 



1. Tric/nfptera. The wings are four, soft, and generally a tube of its own construction. There are many species in this 



transparent ; the upper pair slightly hairy* and the lower countrv, we'l known, in their perfect state, to all lovers of ahg- 



fblded when at rest. The inserts of this order are compar- line. Phryganea rhdmbica (Jig. 967. c) may serve as an ax- 



atively few. The caddy, or cadis worm, is the larva of the ample of this order. 

 spring fly (Phryganea), and lives in the water, concealed within 



2. HymemMcra. The wings are four, clear and transparent. 

 The tarsus (or outer division of the foot) is composed of five 

 joints, and the body is armed with a sting. The bee, the ant, 

 and the wasp, are familiar examples. 



5. Coltdptera. This well defined and most extensive order 

 comprehends all insects known by the name of beetles. They 

 have two wings, concealed beneath a pair of hard wing-cases, 

 which meet close together in a straight line down the back. 

 There are many tribes of these insects, which, both in their 

 larva and perfect state, are extensively injurious to man. 



4. Ortfiiiplera. The irue wings are but two, very large when 

 expanded, and folded lengthways when at rest. They are co- 

 vered, either partially or wholly, by two wing-cases of a thin, 

 tough, and rather opaque substance, somewhat resembling 

 parchment, and reticulated with small nerves. The leading 



roach ; the pest of tropical countries, and frequently trouble- 

 some in our Kitchens and larders. 



5. NeurtJptera. The wings, with very few exceptions, are four 

 in number, clear, transparent, and reticulated with numerous 

 areolets. or irregularly square divisions ; the tail of the female 

 is not armed with a sting. Few, if any, of these insects maybe 

 considered as injurious: some are, indeed, beneficial ; as, from 

 their predatorv'habits, the) attack and devour a vast number 

 of smaller insects- This is more particularly the habit of the 

 green dragon-fly (A'grion vfrgo,,/ig. 967. a', which even one 

 may see, during summer, hovering over ponds, and flying about 

 like a hawk in search of its prey. The Ephemera, or day-fly 

 (E. vulgiita, fig. 967- ft), likewise belongs to this order; "and", 

 although not very numerous in this country, is so abundant on 

 the Continent, that they are collect* d annually in barrows, and 

 alibrd to the agriculturist a rich and valuable manure. 



characters of this order are exemplified in the Clatta, or cock 



1653. The Haustetluta, or suctorial insects, likewise contain five orders. Although apparently destitute 

 of jaws, there is every reason to believe, from the observations of the celebrated Savigny, that the rudi- 

 ments of the masticating organs exist in these insects, but that they are so slightly developed as to be totally 

 useless, and only discoverable under a very strong magnifier. The suctorial insects in their larva state 

 are mostly furnished with strong and well defined jaws, and feed voraciously upon animal and vegetable 

 bodies; yet, from the perfect insect being supported by suction alone, it is obvious that in this state they 

 cai: do no injury to the agriculturist. The orders into which they have been divided are these : — . 



1. LepiMptera. The wings are four, thin, membranaceous, and 

 covered with a fine powdery substance, which, by the magnify- 

 ing glass, is shown to consist of minute scales, lying one upon 

 another, like those on fishes. The butterfly and moth tribes 

 are familiar to every one, as well known examples of these in- 

 sects, the larva of which are called caterpillars. The Papflio 

 urtien?,or small tortoise-shell butterfly ( fig. 968. )> will serve as 

 a good example of the egg (a fl), larva (b), and pupa state (c) of 

 most day-flying hpidopterous insects. 



2. Diptem. The wings are two, clear and transparent, 

 like those of the common house-fly. This order is very nu- 

 merous, and contains many insects which are injurious to vege- 

 tables as larva*, and troublesome to man in a winged state ; as 

 the gnat (Culex), whane-fly (Tabanus), crane-fly (Tipula), &c. 



3. A'ptcra. Entomologists of tbe last century arranged all 

 insects without wings under this order ; but it isnow restricted, 

 by Latreille and Macleay, to such only as have a bivalve articu- 

 lated sheath to their mouth or rostrum, and no wings, as in the 

 case of the common flea. 



4. Hemfptera. Insects of this order are furnished with two 

 folded wings, covered by wing-case , also crossing ovtr each 

 other, of a semi-corneous substance, and which are likewise 

 useful as organs of flight. The tarsi are composed of three, 

 two, or sometimes only of one joint, and the body is much flat- 

 tened. The various insects commonly called Beld-bugs, which 

 emit a strong and disagreeable smell when handled, are all ar- 

 ranged under this order. 



■">. IhmtAptcra. These insects have a great resemblance to 

 the last; but the body, instead of being depressed and flat, is 



