30 ORi)ER OF COLEO^TEHA. 



habits tliaji any of the other orders of insects. Indeed this principle 

 of classification is of value just in proportion as such diversity exists; 

 and where it is very limited, as especially in the great order of Lepi- 

 doptera, it ceases to be available. Even in classifying the Coleoptera 

 upon tliis basis, and at the same time paying the necessary respect to 

 structural considerations, we are sometimes compelled to place insects 

 of similar food habits in several different, and sometimes remote, tribes. 

 The wood-boring beetles, for example, constitute three distinct tribes, 

 designated as the saw-horned borers fBiqjrestidwJ y the long-horned 

 borers fCerambycidfcJ, and the short-horned borers fScolytuhe.J There 

 are likewise four distinct families of fungus-beetles, found respectively 

 in each of the four tarsal sections. But notwithstanding such instances 

 as these, the Coleoptera admit of a very interesting, useful, and, in the 

 main, natural classification in accordan(;e with tlie nature of their food. 



As compared with the other onlers of insects the Coleoptera are sur- 

 l^assed only by the Lepidoptera in the extent of their injuries to culti- 

 vated crops ; and indeed they are so nearly equiil to the latter in this 

 respect, that there may be a doubt which takes the precedence; and it 

 is true of either of these two orders, that, with the exception of the 

 other, it includes a greater number of injurious species than all the 

 other orders of insects combined. The great destructiveuess of the 

 Lepidoptera is readily explained by the nature of their food, nearly 

 all their larvie, commonly known as caterpillars, subsisting upon plant- 

 food, and mostly in a fresh and growing state. The Coleoptera, on the 

 contrary, emlu-ace, in addition to the j)lant-eating species, extensive 

 tribes of predacious and scavenger beetles, which are indirectly of in- 

 calculable benefit to mankind. 



In studying the bearing of scientific upon practical entomology, noth- 

 ing perhai>s is more important than lo trace the connection of the ex- 

 ternal structure of insects with their habits, and especially with the 

 nature of their food ; since we are thus enableil, to a certain extent, to 

 determine the habits of an insect by simi)ly observing the form and 

 structure of its \'isible parts. We are able to lay down some general 

 rules of this kind with respect to the Coleoptera, though most of them 

 are sul>jcct to important exceptions. In order not to give too much 

 spai^e to this part of the sul)ject, we will limit our observatious to two 

 of the most imijortaut and prominent organs — the antennai, and the 

 feet, or tarsi. 



All predaceous beetles have filiform antennai except the lady-birds or 

 Cocciuellidie. 



All the scavenger beetles have strongly clavate or knobbed antennae, 

 except the short-winged scavengers or Staphylinidai, and these are only 

 partial exceptions, as many of them are known to be predaceous. 



