138 . CEREAL AND FORAGE INSECTS. 



THE PUPA. 



The pupal cell is usually found with its long axis inclined or ver- 

 tical, and the pupa lies with the head up. The pupa is easily dis- 

 turbed, and manifests its excitement by very rapid rotation of its 

 abdomen. 



In order to determine the conditions necessary for pupation, 18 

 larvae were divided into three equal lots, and on September 30, 1909, 

 6 were placed on a damp brick and covered with a glass dish, allow- 

 ing them to remain in the light; 6 were placed on a damp brick and 

 covered with a tin box, excluding the light, and the remaining 6 were 

 shut in the dark in a dry paper box. Two of the first lot had pupated 

 October 13, on the 16th 2 more, and on November 3, 2 adult beetles 

 were found, all the others being dead. In the second lot 3 had 

 pupated on October 13 and on the 16th 2 more. Three adults had 

 emerged November 3. None of the larvae in the dry box pupated, 

 showing that while earth and darkness are not essential to pupation 

 moisture is. 



The pupal period was determined in a great number of cases. 

 During the fall of 1908 especially, large numbers of the larvae were 

 collected and placed in small jars containing damp sand, so that the 

 date of emergence of the adult beetles could be easily observed. 

 Below is shown the time elapsing between the entranee of the larvae 

 into the sand and the emergence of the adults: 



5 beetles emerged in 14 days. 

 36 beetles emerged in 15 days. 

 72 beetles emerged in 16 days. 

 169 beetles emerged in 17 days. 

 72 beetles emerged in 18 days. 

 49 beetles emerged in 19 days. 

 26 beetles emerged in 20 days. 

 5 beetles emerged in 21 days. 

 1 beetle emerged in 22 days. 

 1 beetle emerged in 23 days. 

 21 beetles emerged in 24 days. 

 1 beetle emerged in 25 days. 



This gives for the 458 beetles an average of 17.4 days spent under- 

 ground. Subtracting from this the 6 days spent as a larva under- 

 ground, the actual pupal period is determined as being about^llj 

 days, with extremes of 8 and 19. 



THE ADULT. 



The beetles push slowly up through the soil and are quite active 

 when newly emerged. They seem never to fly, but in the field are 

 very ready to "play possum," and drop to the ground at the least 

 disturbance. In falling they do not draw up their legs, but leave 

 them extended, and for this reason are much easier to find on the 



