544 FAMILY XVIII. — EROTYLIDJE. 



a. Last joint of palpi widely hatchet-shaped; thorax yellow with four 

 black spots; length 7-8 mm. V. Ischyeus. 



(hi. Last joint of palpi oval or slightly triangular; thorax yellow or black, 

 rarely with two spots ; length less than 6 mm. 

 e. Middle area of mentum large, transverse. VI. Mycotbetus. 



ee. Middle area of mentum small, triangular. VII. Teitoma. 



II. Plceosoma Woll. 1854. 



This genus is represented in the eastern United States and In- 

 diana by a single very small brown species. 



1037 (3212). Plceosoma punctata Lee. Trans. Amer. Ent. Soc. V. 1875. 



171, 



Oval, rather strongly convex. Uniform dark chestnut-brown; antenna* 

 and legs paler. Thorax twice as wide as long, finely and sparsely punctate. 

 Elytra distinctly but rather sparsely and irregularly punctate, and nar- 

 rowed to a rounded apex. Length 2-2,5 mm. 



Southern two-thirds of State: common. Hibernates. April 9- 

 December 3. Gregarious in winter and early spring beneath bark, 

 especially that of elm and willow. 



III. Dacne La.tr. 1796. (Gr.. "bite or sting.") 



This genus is represented in the United States by three small 

 species, one of which ocenrs in Indiana. 



1038 (3213). Dacne 4-mactjlata Say, Bost. Journ. Nat. Hist.. I, 1835, 169; 



ibid. II. G45. 



Oblong, parallel. Black ; elytra each with a round reddish-yellow spot 

 on humerus and another at apex; beneath piceous or dark reddish-brown, 

 the antenna), legs and clypeus paler. Head and thorax closely but sparsely 

 punctate ; elytra with numerous rows of fine punctures. Length 2.5-3.2 mm. 



Throughout the State, frequent in the southern counties; less so 

 northward. April 15-September 21. Occurs in fungi. 



IV. Megalodacne Crotch. 1873. (Gr.. "large + bite. ") 



Here belong the largest species of the family, handsome black 

 and yellow forms, having the fourth joint of tarsi smaller but dis- 

 tinct; last joint of palpi subcylinclrieal and the mentum triangular. 

 Three species are known from the United States, all of which occur 

 in Indiana^. 



key to tndiana species of megalodacne. 



a. Elytra without rows of punctures; length 1S-21 mm. 1040. iteeos. 



aa. Elytra with rows of fine punctures. 



