248 



B. H. GRAVE 



April 15. Two of them changed to pupae before April 20. 

 One of these pupae emerged as an adult on Ala}" 7, making the 

 duration of the pupa about three weeks or less. 



Since the first pupae were found, under natural conditions, 

 on May 25, and since the number of pupae in the soil was con- 

 siderably reduced before June 15, it would seem that the duration 

 of the pupa under natural conditions is also about three weeks. 



The following table gives a record of the date of appearance, 

 and measurements of beetles as they emerged from the breeding 

 boxes. 



DATE OF EMERGENCE 



April 4 

 April 5 

 April 7 

 April 11 

 April 12 

 April 1.5 

 April 17 

 April 18 

 April 25 

 April 26 

 Max 7 



NUMBER OF 



BEETLES 



MEASUREMENTS 



m m . 



3.5 



4.5 



4.5 

 .3.5 and 4.5 



4 

 3.5 and 4.5 



4.5 



3.5 



3.5 



4.5 



4.5 



It will be noted that there are two sizes. Those marked 

 3.5 mm. varied between three and one-half and four millimeters 

 while those marked 4.5 mm. varied between 4.5 and 5 mm. In 

 all probability the larger ones are more nearly normal. The 

 disparity in size is apparently not due to a difference in sex. 

 The table also shows that beetles emerged during the period 

 of a month under laboratory" conditions. 



Under normal conditions the first pupae were found on Alay 25 

 and the last larvae about June 15. It is apparent therefore 

 that beetles may continue to emerge for a considerable period, 

 and this fact should be taken into account in attem]:)ting to spray 

 for the eradication of the pest. 



