112 THE ORDER OF COLEOPTERA. 



The antennae, in all the Trachelides are of nearly or the same width 

 throughout, sometimes simple or filiform, sometimes serrate, and some- 

 times pectinate or branched, especially in the males. The elongated 

 coxse permit great freedom of motion to the legs ; and their frequently 

 bright or diversified colors show that they live exposed to the light of 

 the sun. Accordingly we find that in their matured state they are 

 active diurnal insects, often frequenting plants and flowers. 



We have designated the insects of this tribe as parasitic beetles, a 

 title which preeminently, but not exclusively belongs to them. The 

 term parasite literally means one who sits at the table of another, and 

 lives at his expense, and is now very commonly applied to those insects 

 which either inhabit the nests of other insects and subsist upon the food 

 prepared by them, or which infest the bodies of other insects, feeding 

 upon their substance, and ultimately causing their death. This para- 

 sitism is found to be very extensive in the insect world, and to consti- 

 tute one of the most efiicient agencies by which the excessive increase of 

 many kinds of insects is kept in check. The great majority of parasitic 

 insects is found in the order of Hymenoptera, where they comprise some 

 of the most numerous of tbe families of insects. In the order of Coleop- 

 tera the parasitic species are comparatively few, and outside of the pres- 

 ent tribe, are mostly limited to a small number of minute species in the 

 families Staphylinidne, Pselaphidje and Scydma?nid:e. The parasitic 

 character is therefore the more distinctive of the i3resent tribe, most of 

 the families of which are parasitic in their larva state ; though it is pret 

 ty well determined that a few of them are lignivorous, and the larvjp. 

 of some of the families are but little known. The Lagriidre and Anthi- 

 cidse, from certain observations which have been made upon them, are 

 supposed to be carnivorous, and Latreille considered the latter to be par- 

 asitic. The Rhipiphorida3, Stylophida?, and MeloidtTi, including the sub- 

 family of lloriides, are known to be parasitic. The larviie of the Pyro- 

 chroida^. and Mordellidie are found in wood, upon which, therefore, they 

 are supposed to feed. Mr. Eiley has found the Mordella 8-punctata, 

 and its larv;v, (Fig. 50) in very rotten oak stumps, and he states there 

 can be no doubt of its lignivorous habits, as he has found the larv;e in 

 their own burrows, extending through the wood in all directions. He 

 has likewise bred a smaller sj)ecies from the green stems of ambrosia, 

 and other herljacious plants. In a strict classification according to the 

 habits, therefore, the Pyrochroida^ and Mordellidie would require to be 

 separated from the parasitic fannlies, but there appear to be no organic 

 characters which these two families i>ossess in common, which author- 

 izes us in x>lacing them in a tribe by themselves. 



It is one of the many remarkable facts in the natural history of insects 

 that the same species often differs greatly in its habits and the nature of 

 its food, in the different stages of its existence. We have had occasion 



