April, '17] HAYES: LIGYRUS GIBBOSUS 259 



to a light brown, the abdominal segments remaining somewhat lighter 

 than the rest of the body. As a rule, the pupa lies on its back. The 

 only movement discernable is a slight twisting of the abdomen. Sec- 

 ondary sexual characters (to be described later) can be seen through the 

 pupal skin and the sexes are thus easily determined in this stage. The 

 average length of the pupal period was found to be 19.1 days, with a 

 maximum of 29 days and a minimum of 11 days. The first pupa of the 

 season was found on July 30, and the last near the end of October. 

 The Adult. — The adult (PI. 12, fig. 1) is a large, cumbersome, brown 

 beetle, often mistaken for one of the June-bugs or May-beetles, al- 

 though the circular depression of the thorax with its small tubercle and 

 the strongly punctured elytra easily distinguishes it from them. The 

 size varies from 11 mm. to 16 mm., the males usually, though not 

 always, being the smaller. 



L. gibbosus may be described as follows: robust, convex, rather broadly oval, 

 sUghtly wider posteriorly, reddish-brown to blackish, somewhat paler on ventral 

 surface, moderately shining. Mandibles three-toothed on outer edge. Labial 

 palpi inserted at sides of mentum. Antennae lamellate, 10-jointed. Clypeus 

 subtriangular, bidentate at distal edge, proximal margin with transverse carina. 

 Clypeus and head with large confluent punctures. Eyes finely granulated, outer 

 margin of head in front of eyes distinctly carinated. Thorax wider than long, sides 

 regularly rounded from base to apex, flaargin slightly reflexed. A small tubercle at 

 apex, followed caudad by a large circular depression. Surface finely punctate, 

 punctures sparse and irregularly placed. Ventral surface of thorax and legs with 

 long, dense, brown hairs. A small tubercle directly behind front coxa;. Anterior 

 tibiae tridentate. Middle and posterior tibiae, each with two pubescent carina on 

 outer edge, giving appearance of extra corbels. Punctures of elytra coarser than those 

 of thorax, in nearly regular rows on disk, at sides irregular. Scutellum very sparsely 

 punctured. Elytra subtruncate at tip. Pygidium exposed, triangular, finely and 

 sparsely punctate. Ventral segments of abdomen smooth, shining, each with more 

 or less distinct transverse row or setigerous punctures near outer margins. Distal 

 margin of last ventral segment of male distinctly emarginate; of female, broadly 

 rounded. 



The sexes are distinguished by the characters of the last ventral 

 abdominal segment. In the male, there is a distinct emargination at 

 the distal end of this segment, while in the female its margin is obtusely 

 rounded (PI. 12, fig. 5-6). 



When handled, the adults often excrete a white viscid fluid from the 

 posterior end of the abdomen. They will extrude this liquid even when 

 freshly transformed from the pupa. At this time the elytra are creamy 

 white but change in a few hours to the characteristic brown color. 



The beetles are attracted to lights at night. During the day, they 

 burrow into the soil or hide beneath such objects on the ground as will 

 give them shelter from the light. Mating occurs underground and in 

 the darkness of these hiding places. During the past year, overwin- 



