230 



COLEOPTERA 



CHAP. 



Fam. 26. Histeridae. Very compact beetles, with very hard 

 integument, short, bent antennae, with a very compact club : no 

 hypoglottis. Elytra closely applied to body, but straight behind, 

 leaving two segments exposed. Abdomen with Jive visible ventral 

 segments; with seven dorsal segments, all hard. Front coxae 

 strongly transverse, hind coxae ividely separated. The extremely 

 compact form, and hard integument, combined with the peculiar 

 antennae consisting of a long basal joint, six or seven small 

 joints, and then a very solid club of three joints covered with 



minute pubescence render 

 these Insects unmistakable. The 

 colour is usually shining black, 

 but there are numerous depar- 

 tures from this. The way in 

 which these Insects are put 

 together so as to leave no chink 

 in their hard exterior armour 

 when in repose, is very remark- 

 able. The mouth - parts are 

 rather highly developed, and 

 the family is entitled to a high 

 rank ; it consists at present of 

 about 2000 species ; l in Britain 

 we have about 40. The larvae 

 are without ocelli or labrum, 

 FIG. \io.-piatysoma depressum. Europe, but have well-developed mandi- 



A, Larva (after Schiodte) : B, perfect , -, , , , . 3 



insect, bles, the second arid third 



thoracic segments being short, 



the ninth segment of the abdomen terminal, with two distinctly 

 jointed cerci.'^ Histeridae are common in dung, in carcases, decay- 

 ing fungi, etc., and some live under bark these being, jn the 

 case of the genus Hololepta, very flat. Some are small cylinders, 

 elaborately constructed, for entering the burrows of Insects in 

 wood (Trypanaeus) ; a certain number are peculiar to ants' nests. 

 Formerly it was supposed that the Insects were nourished on 

 the decaying substances, but it is now believed, with good reason, 

 that they are eminently predaceous, in both larval and imaginal 



1 The family was monographed by the Abbe de Marseul in Ann. Soc. ent. France, 

 1853-1862, but great additions have been made since then. 



2 For characters of larvae of various genera, see Ferris, Larrcs, etc. p. 24. 



