GRAPEVINE ROOT WORM 25 



therefore responsible to a limited degree for the very extended 

 period during which adults are found abroad. Most of the grubs 

 complete or nearly complete their growth in the early fall, and on 

 the approach of cold weather descend deeper in the earth. Pro- 

 fessor Webster records finding the grubs a foot below the surface 

 in the spring, and our own observations indicate that they descend 

 nearly to that depth, where they pass the winter in small oval 

 cells. Their ascent in the spring occurs after the appearance of 

 warm weather and probably some time in early May. Experi- 

 ments in 1903 with grubs collected the latter part of April 

 demonstrated the ability of full grown and apparently half grown 

 larvae to complete their transformations with no more nourish- 

 ment than is found in ordinary garden soil in which there are no 

 grape roots. Those about quarter grown were not able to sur- 

 vive the test. On the other hand, some nearly full grown individ- 

 uals were observed last spring feeding on the roots to a slight 

 extent in our breeding cage. 



_ Pupa. Professor Webster records the finding of a very few 

 pupae as early as the first week in June, and Mr Barden states 

 that in 1902 he observed the first pupae at Ripley June 7, though 

 Mr Hough is of the opinion that the larvae began to transform 

 as early as June 4. The great majority of the insects had trans- 

 formed to this stage by Jun^ 23. The present season was con- 

 siderably more advanced than that of last year, and 90^ of the 

 insects were in the pupal stage May 29, 1903, on light sandy loam. 

 The cells are almost entirely within 2 or 3 inches of the surface 

 and usually within 2 or 3 feet of the base of the vine. 



The duration of the pupa stage has been stated by earlier 

 writers as about a fortnight and actual observations with breed- 

 ing cage material have enabled, us to determine this period as 

 from 13 to 14 days. These observations were made in the oflSce, 

 where temperature conditions were uniform and rather high, 

 and it would not be surprising if this period was materially 

 extended out of doors in unusually cool weather. 



The oval cells occupied by the larvae can be broken repeatedly, 

 and the grubs will make others, but such is not true of the pupae. 

 The insects are so delicate in the latter stage that the writer has 

 experienced great difliculty in transmitting them through the 

 mails, even with most careful packing. This is shown by the fact 

 that out of 58 mailed to Albany only 15 arrived alive ; a number 



