BEETLES. 299 



one autliority to be species \rill be only varieties in tlie estimation of anotlier equally 

 able coleopterologist. Gemminger and Harold's catalogue of the Coleoptera of the 

 world, issued in parts between 1868 and 1876, contains 77,008 species described up to 

 the time of issue. Counting omissions from this catalogue, and species described 

 since its publication, the number of described species must now reach or exceed 

 100,000. In large collections there are, in all prol)aI)ility, between 2ti,(iO() and 30,000 

 more species still waiting dcscrijition, and it would be rash to predict the number of 

 species which will be found later in parts of the world as yet insufficiently explored. 

 In Xorth America, north of Mexico, Crotch's list, published in 1874, enumerates 7,450 

 species, and Mr. S. Ilenshaw, who has a manuscrijit catalogue of beetles of the above 

 region kept up to date, informs me that the numVier is now (1884) about 8,950. 



Sjjecies of insects which feed upon substances of commercial value belonging to 

 one region are often transported, in one way or another, to other regions, where it is 

 not unconnnon that these immigrants become serious j)ests until their natural enemies 

 are also imported, or until predaceous animals of their new home resort to them for a 

 food supply. Thus the Cnlnrado jjntato-beetle {Dori/iihora decemUneuta) has spread 

 from its original habitat in Colorado over the eastern United States, and its advent in 

 Europe is so greatly feared that it has been a subject of legislation in several coun- 

 tries. Our troublesome carpet-beetle {Anthrcuus scrop/aihtriu;) was probably intro- 

 duced from Europe, and the asjiaragus-beetle of Europe {C'riocei'is aspuva;/!) was an 

 immigrant that landed on Long Island, near Xew York city, some time about 1800, 

 and has since done considerable damage to the nuirket gardens which suiij)ly Xew 

 York city. So, too, the meal-beetle ( Tenebrio inoUtor), and the grain-weevil ( Cahin- 

 (/)•<( ortjzii) are of European origin. A few sjiecies of beetles have become, by mi- 

 gration, almost cDsmopolitan, liut the greater numlier of sjiecies are confined to one 

 continent, often to some small part of a continent, although lieetles are found in every 

 jiart of the world that has been exjilored. 



In geological distribution Coleoptera have l)een found as carlv as the carboniferous; 

 they are more common in Jurassic strata, and still better rejjresented in the tertiary 

 and in amber. 



The modes of collecting and preparing beetles for the cabinet are very varied. 

 The beginner usually depends for sjiecimens ujion lucky finds, upon captures witli the 

 net, and upon such modes of collecting as are used for all kinds of insects, and which 

 are described in most general works on entonmlogy, while the experienced coleoii- 

 terist studies the habits of rarer insects, and uses baits and traps to ensnare them. 

 Some of the less-km)wn and useful ways of obtaining Coleoptera for the cabinet are 

 the following, lieetles and their larvw which inhaljit dung, earth, or other materials 

 heavier tlian water, float to the surface of water, and can lie easily discovered if the 

 earth or dung be broken u]i and placed in still pools, or in a trough filled with water. 

 For killing many kinds of beetles a 'cyanide bottle' is very useful: this bottle is 

 made by putting a few pieces of potassic cyanide into the lidttum of a large-mouthed 

 bottle — a horse-radish bottle will do very well, if no larger one can be found — and 

 covering the pieces of cyanide with dry plaster of jiaris ; after the plaster has been 

 evened down by shaking the bottle a little, water should be added, best a spray from 

 an atomizer. When the jilaster sets a firm shell will be formed, which will hold the 

 cyanide in its })lace, while its poisonous vapors will slowly escape through the plaster. 

 If the moistened and suljsequently hanlened portion of the plaster is only about as 

 thick as is the glass of the bottle itself, a condition of affairs which can be regulated 



