ANNUAL REPORT, 1940 71 



On potted grape vines in tlie insectary, mated beetles averaged 3.13 

 oviposition punctures per female, but observations indicate a greater ovi- 

 position activity in the field. The average life of 21 indivifluals reared in 

 the insectary from oviposition to adult was 54.55 days. 



When burrowing in the cane, most of the larvae work toward the base 

 of the cane rather than toward the tip, and when control by hand picking 

 is practiced, the infested cane should be removed well below the lowest 

 girdle. 



Spraying experiments with cryolite and fish oil gave moderate protec- 

 tion, hut during the most rapid growth of the grape canes applications 

 at weekly intervals permitted considerable girdling between treatments. 



Parasites of the European Earwig. (W. D. Whitcomb, Waltham.) In 

 order to follow up tiie liberation of parasites in the Fall River-Taunton 

 area in 1939, twenty earwig traps or hiding blocks were placed in June 

 1940 in the localities where parasites had been released. These were 

 examined in July, August, September, and October, but no specimens of 

 the earwig parasite, Bfgo}iichaeta sctipennis, were recovered. 



The earwig population throughout the infested area was less than in 

 1939, especially in Fall River where the number recovered in traps was 78 

 percent less. In the Somerset — Taunton area, the number of earwigs 

 captured was 26 percent less than in 1939. 



Insects Concerned in the Dispersal of Dutch Elm Disease. (W. B. 



Becker.) Mr. W. E. Tomlinson, Jr., at the Waltham Field Station again 

 cooperated by continuing experiments with the native elm bark beetle 

 and the smaller European elm bark beetle. The following data were 

 taken. 



The Native Elm Bark Beetle, Hylw^gopinus rufipcs {Eich.). In the logs 

 (mentioned in last year's report, page 66) from hurricane-felled trees in 

 which eggs were laid in early June 1939 and from which adults began to 

 emerge on July 29, 1939, emergence was observed to continue until No- 

 vember 3, 1939. No emergence was observed from these logs during 1940. 



The Stnaller European Elm Bark Beetle, Scolytus multistriatus Marsham. 

 In the logs (mentioned in last year's report, page 66) from hurricane- 

 felled trees in which eggs of this species were laid in early June 1939 ar. i 

 from which adults began to emerge on July 20, 1939, the emergence was 

 observed to continue until September 10, 1939. Emergence was again 

 observed from these same logs on June 5, 1940, and continued until July 

 22, 1940, (173 beetles emerged during 1939 whereas 883 emerged during 

 1940 from the same caged material). 



Scouting for Elm Bark Beetles. (W. B. Becker.) In conjunction with 

 Dr. D. O. Wolfenbarger of the Dutch elm disease laboratory at Morris- 

 town, New Jersey, scouting for Scolytus multistriatus was carried on in 

 various parts of Massachusetts, especially in places where spread was 

 most suspected. Adult beetles were found in Western Massachusetts at 

 Richmond Furnace, Stockbridge, West Stockbridge, and Monterey, and 

 in eastern Massachusetts at Marlborough and East Pepperell — all loca- 

 tions where they had not been previously found. 



