261 



INSECT A. 



INSECTA. 



262 



The former was established when entomology was, comparatively 

 speaking, in its infancy ; and although Fabricius possessed a more 

 intimate acquaintance with insects, yet he contended that an artificial 

 classification should be adopted till further discoveries had cleared 

 the way for their satisfactory development. We cannot feel surprised 

 therefore that these systems should have been superseded by others 

 more modern. 



The system of Burmeister is founded upon philosophical principles ; 

 we are not however prepared to agree with him in all instances. We 

 allude more particularly to his order Dictyoptera, the species of which 

 oupht, we think, to be incorporated with the Orthoptera. 



The following arrangement is that given by Mr. Westwood in his 

 ' Introduction to the Modern Classification of Insects :' 



Class of Hexapod Metamorphic Insects. 



Sub-class, Mouth with Jaws. Sub-class, Mouth with a Sucker. 



(Dacnoitomata, W.) (Antlioitomata, W.) 



Order ffymrnoptera. Order, Diptera. 



? Osculant order Streptiptera. ? Osculant order, Uomaloptera. 

 Order Coltoptera. 



Osculant order Euphxoptera. ? Osculant order, Aphaniptera. 



Order, Orthoftera. Order, Heteroptera (including 



?(77< the Water-Bugs). 



Order, Newroptera. Order, Homoptcra. 



Order, Trickoptera (Phryganea Order Lepidoplera. 

 alone). 



The mutual affinities and likewise the grade of perfection of the 

 various orders, may be expressed by arranging them in the following 

 succession : 



1. Hymenoplera. 5. ffemiptera. 



2. Coleoptera. 6. Homoptera. 

 8. Orthoptera. 1. Lepidopttra. 

 4. Neuroptera. ' 8. Diptera. 



The number of species of Insects is much greater than that of any 

 other class, and they are probably as numerous as all other forms of 

 animals put together. Although possessed of extraordinary locomo- 

 tive power*, they are each and all distributed within as certain bounds 

 as the most stationary animals or plants. Independent, then, of its 

 great interest as a part of philosophical zoology, the study of the 

 range and specific centres of the forms of insect life becomes of great 

 importance as an aid in the definition of tribes, genera, and species. 



Climate and the extension or form of land are the chief influences 

 regulating the distribution of insect life. The constitution of the 

 soil affects it also, but in a secondary manner, through its influence on 

 the vegetation, on which many insects feed. When from the inter- 

 vention of tracts of water, of mountain barriers, or other causes 

 depending on ancient geological events anterior to the origin of the 

 existing Fauna of the earth, tracts of land presenting exactly similar 

 conditions of climate and soil are placed far apart, we then have, not 

 a repetition of the same forms among their insect population, but a 

 representation by similar forms. This we see also in the Fauna of the 

 several zones of climate belting mountains at different heights. Man's 

 agency and the transporting power of currents of wind modify the 

 distribution of many species of insects. In the following brief glance 

 at the distribution of the principal genera of insects, examples of all 

 these influences will be met with. 



Coleoptera. From the facility with which insects of this division 

 may be preserved and trasported from place to place, we have more 

 detailed accounts of their distribution than of any of the species of 

 other orders. The Cincindelidie are dispersed over most parts of the 

 globe, the typical genus being cosmopolitan, whilst other groups are 

 more limited. Among the Curabidie are many genera peculiar to 

 Europe. Chlctniut, Agonum, and Amara, are common to both hemi- 

 spheres. Jfa>-palut and Brachinut are cosmopolitan. Cnemacanthu 

 occurs in Africa and Chili. The Carabidce of Western Asia agree 

 remarkably with those of Europe. Erichson has remarked that Carabi 

 are very constant to certain soils : the vertical distribution of the 

 species is also very constant. The water-beetles allied to Dytiscus, 

 itself universal in the Old World, are mostly European : several of 

 the species live in salt or brackish waters. Gyriniu ranges from 

 Northern Europe to Australia. The Braclielytra have their chief 

 centre in Europe. The typical genus Staphylinut appears however to 

 be represented everywhere : many species occur in South America. 

 A species of Altochara is found in Van Diemen's Land. Slater and 

 Jlupreitii, types of families, are both cosmopolitan : the species are 

 often local, and their dintribution depends, in many cases, on that of 

 certain plants on which the larva,- prey. Among the Fire-Flies (Lam- 

 pyrid<e) the genus Lampyrit, which is European, is represented in 

 the tropics by Photinut, and in the New World by Atpiioma. The 

 Malachii are found everywhere, except in South America. Ptinus, 

 a genus chiefly European, has a single representative in Australasia. 

 Of the A'ecrophagi, the genera Cryptophayus, Stronyylus, and Silpha 

 are found everywhere, ranging from Britain to China, and from Brazil 

 to Lapland, flitter, the type of a family, is also a cosmopolitan 

 genus. liyrrhua belongs to the northern hemisphere, and has its chief 

 in Europe. Among the Coprophagous Lamellicornei, the genus 

 Aphodiut, though represented in most countries, is chiefly developed 



in temperate regions ; whilst Ateuchus, on the other hand, is mainly 

 tropical. Geotrupes is cosmopolitan. Copris ranges to Australia, 

 where however it is confined to the north coast. Scarab&wa is sub- 

 tropical. Pelidnota is American. The beautiful Cetonice appear to be 

 of universal distribution. The strange forms of Goliat/ms are South 

 African. Of the cockchafers, Melolontha is cosmopolitan ; Macrotops 

 and A noploffnalhus, confined to Australia ; Hoplia, with one exception, 

 European: Amphicoma, is Mediterranean; Anisoplea and Serica are 

 natives of the warm and temperate regions of both hemispheres, whilst 

 Euchlona, occupying the same range, extends beyond in a northern 

 direction. Of the Melasomce, Slaps and Pimelia, both extensive 

 genera, have their chief development in the warmer regions of the 

 Old World. Of the Stenilytra, Helops is cosmopolitan, (Edennra 

 European. Of the Anthicidte the numerous species of Antlticits are 

 chiefly inhabitants of temperate regions. The Blistering Beetles of 

 the genus Mel'tie are very generally distributed. 



Of the ten thousand species of Weevils the great genera Cenlor- 

 hynchus, Cryptorhynchus, Calandra, Otiorhynchns, and Cliomts are all 

 cosmopolitan. Platysomil and Cyphus are South American ; Erachy- 

 cerui. South African and Mediterranean. rentus,- mainly confined to 

 the tropical regions of both hemispheres; Apion and Rhynchites, chiefly 

 European. The distribution of the species of weevils depends in a 

 great measure on that of plants. 



The most beautiful and vividly coloured forms of Longicorn Beetles 

 are mostly tropical. The presence of forests determines that of many 

 of the genera. Of the seventy genera of Cerambycidce, the typical 

 one, Cerambyx, is cosmopolitan. Others have defined centres, as 

 Clytui in Europe, Tracliyderes, in South America. 



Of the Chrygomelinoe, the typical genus C'ltrysomela is cosmopolitan. 

 Tho presence of certain plants determines the distribution of the 

 species. From this cause, species of limited distribution are some- 

 times multiplied far from their aboriginal centres. Thus Galeruca 

 calmarimsii, introduced from Europe into America, multiplied so at 

 Baltimore in the years 1838 and 1839, that the elm-trees of the district 

 were eaten bare by their larva), and probably they will henceforth 

 become a constant annoyance in the New World. Lema and Donacia 

 are instances of cosmopolitan genera having distinct centres in tem- 

 perate climates. Cassida, on the other hand, has its centre in the 

 Irate 



Of the Trimera, Coccinella are found everywhere. Eumorphut is 

 Indian and Polynesian. 



Orthoptera. Though by no means an extensive order either as to 

 genus or species, the Orthoplera are of very general distribution. 

 Representatives of the genera Grytliis and Acheta, the grasshoppers 

 and crickets, are found in most countries. The Locusts are mostly 

 exotic. The strange Phasmce are mostly tropical, as are also the 

 greater number of Mantidce, known popularly as ' walking leaves.' 

 The Cockroaches, Blatlce, are very general, and have been greatly 

 diffused from their original centres by unintentional human agency. 

 The Earwig tribes, Forficulidte, including more than fifty species, are 

 in great part European, but range even to Van Diemen's Laud. 



Erichson notices the curious fact respecting the Orthoptera of Van 

 Diemen's Land, that only one fourth of the species are completely 

 winged and capable of flying. 



Neuroptera. The number of known species in this order is shori 

 of one thousand. The section of Pliclpennes is almost entirely Euro- 

 pean ; the genus Macronoma, including species from Madagascar and 

 Brazil, is an exception. The Planipennes, a great part of the genera 

 of which division are now considered by many naturalists Orthopte- 

 rous, have a much more varied distribution. Thus the Myrmelionidce 

 are cosmopolitan, the Perfa and Nemouras chiefly European, the 

 Panorpix characteristic of the temperate regions of both the Old and 

 and New World, the Termites of the tropics. In the section of Subuli- 

 cornel, the Ephemeridce are European ; the ^Kshnidte, cosmopolitan ; 

 as also the true Dragon-Flies, Libellula;, of which near two hundred 

 species are known. Other allied genera are more limited. 



Uymenoptera. Among the sting-bearing species, the true bees are 

 characteristic of the ancient continent, those now dispersed in America 

 having been transported from Europe. The genera Centru and 

 Eu/jlossa are exclusively American. Nomia is Asiatic. Allodape is 

 south African. Andrena, Xylocopa, and several other extensive genera, 

 are cosmopolitan. A great many genera of wasps are peculiar to 

 South America. The ants are most developed in Europe. Bembex is 

 a tropical genus. The terebrating Ifymenoptera are botli very numer- 

 ous and widely distributed, especially the great genus Ichneumon. 

 Certain genera forming the family O.ryurce are exclusively European, 

 as are also a great part of the numerous family of Chalcididce. Cynips 

 is European, and the greater number of Tenthredinidae. 



The distribution of the Strepaiptera depends on that of the insects 

 on which they are parasitic. 



Lepidoptera. When the distribution of the butterflies shall have 

 been worked out, it will doubtless prove very interesting. At present 

 our knowledge of this subject is imperfect. The Papilionidce are 

 very numerous specifically, and for the most part tropical. Some of 

 them possess great ranges. Thus certain species of Picris are found 

 over all Europe, and great part of Asia and Africa. Other forms are 

 constant to mountainous regions. Of the Nymphalidte the greater 

 number and more gorgeous forms are tropical. In this family there 



