382 



NATURAL HISTORY OF ARTHROPODS. 



species with brownish legs an<l antenna?, and about 0.2 of an inch long, is often very 

 abundant in flowers of the wild morning-glory ( ('alijstegia sejnum) in the northeastern 

 United States. 



Separated from the sjjecies of tlie preceding family by their slender tarsi, of which 

 the first joint is sliort, are the Trogositir.e. Of this family there arc two groups 

 readily distinguished by their form. The species of the first group are elongate insects 

 with the jirothorax narrowed behind. Trogosita muwUamca is a cosmoi)olitan 

 species of this group. It is deep l)rown, flattened, and about 0.4 of an inch long. The 

 species of Trof/osita are often found under decaying bark, but certain of them have 

 proved to be very injurious to grain, and to other articles of commerce. Thymahis 

 fulgidus is a common representative of the second grouji of tlie Tro- 

 gositidas, which contains oval species. This is a nearly round, some- 

 what flattened specie.s, about 0.2 of an inch long, which abounds on 

 Poli/ponrs hefultniis, a large, white fungus that is pai-asitic on trunks 

 of dead birch trees. The beetle is a slightly shining bronze c(jlor, and 

 is both ])unctate and pubescent. Its larva is <l.3 to 0.4 of an inch long, 

 somewhat flattened, and has the anal extremity armed with two parallel, 

 acute, corneous processes, along the sides of which are a few sharji, short 

 branches. The larva, which is of a liyaline white with a yellowish head, has five ocelli 

 on each side of the head. Tlie larv» generally destroy the tough tissue of the above- 

 mentioned fungus during the early spring, in the eastern United States, and pujiate in 

 the remnants of their food-plant, the beetles emerging during the summer. 



A considerable number of small beetles that are, for the most part, round, haixl, 

 and seed-like in appearance, and generally live upon decaying animal or vegetable 

 matter, are united in the family Histeeid.e. They differ systematically from the Ni- 



FlG. 446. — Tio- 

 gosita maiirl- 

 tanica. 



Fill. 447. — //istvr n.iriiutai. 



Fig. 448. — Histt r bimacuhitus. FiG. 449. — Onfhrophilus atterjiatus. 



tidulidre in having geniculate antenna'. Most of the Histerida? are black, a few liave 

 red spots, and a small number are metallic in coloration; all their tibia? are usually 

 dilated ; the elytra are truncate behind, leaving two abdominal segments exposed ; the 

 upper surface is striate, tlie position and naiure of the striiB being generally of value 

 as specific characters. The larva? of the Histerid;e are elongated, with corneous head 

 and prothorax, .and have no ocelli. Some species of tliis family inhabit ants' nests, a 

 few live under bark. Ilisfcr lielluo is known to eat larvse of Agelastica alni, and //. 

 pustulosiis drags the larva? of Agrotis, a noctuid moth, from their holes and devours 

 them, in comjiany with others of its species that hasten to the repast. 



In the species of Saprimis the head is bent downward and retracted ; the jirotho- 

 rax is truncate anteriorly, and has cavities at its side for the reception of the antennae, 

 which are inserted beneath the front. There are nearly sixty North American species 



