April, '19] McCOLLOCH: ELEODES OPACA 187 



Larva. — As pointed out by Swenk (1909, p. 335) the larva of Eleodes 

 opaca (Plate 8, B) closely agrees with the description of E. dentipes as 

 given by Blaisdell (1909, pp. 497-499). The minor differences have 

 already been discussed by Swenk, and need no further treatment. On 

 hatching, the larvae are about 2.8 mm. in length. Growth is compara- 

 tively rapid and by fall the worms are about full grown, being from 21 

 to 23 mm. in length. 



The larvae moult eleven times, including the moult when pupating, 

 between hatching and pupation, the time between moults varying to 

 some extent. An average of the length of each stadium, as determined 

 for six larvae, is as follows: first stadium, 4 days; second stadium, 3 days; 

 third stadium, 4 days; fourth stadium, 6 days; fifth stadium, 8 days; 

 sixth stadium, 13 days; seventh stadium, 15 days; eighth stadium, 12 

 days; ninth stadium, 18 days; tenth stadium, 199 days; eleventh sta- 

 dium, 20 days. In moulting the skin is split on the dorsal side from 

 the vertex back to the first or second abdominal segment, and the old 

 skin is shed by the larva arching the back and drawing the body out, 

 the posterior end emerging last. 



The larvae are subterranean in their habits, and thus far the writer 

 has never observed them on the surface of the ground. Swenk (1909, 

 p. 333), however, cites a case where they were found in large numbers 

 on the surface following a heavj^ rain. They show a preference for 

 rather dry soil, and usually the majority of the worms are found at the 

 junction of the loose drier soil with the compact moist soil. In the 

 fall they are found at the bottom of the drill rows where they are feed- 

 ing on the seed wheat. In the spring they are more often located just 

 beneath the surface of the ground, under clods and wind-blown soil. 

 The principal food of the larvae appears to be wheat kernels, but they 

 also feed on the roots and seeds of native grasses and weeds, and on 

 decaying matter. In the rearing work, the worms thrived best on 

 soaked wheat and bran. During the spring of 1918, considerable in- 

 jury was also done to germinating oats, barley, corn, and sorghums, 

 where these crops had been planted on infested wheat land. The larvae 

 also feed on their cast-off skins and on larvae that are dead or in a 

 weakened condition. 



Most of the larvae become practically full grown by October, and 

 thus pass the winter. Early in the spring they become active, and 

 usually moult once during April. Pupation occurs during the last of 

 April and throughout the month of May. The transformation to the 

 pupal stage is preceded by a semipupal or quiescent state lasting about 

 a week. The length of the larval stage as determined for tlie several 

 years that the work has been in progress is shown in the following table: 



