66 MASS. EXPERIMENT STATION BULLETIN 388 



Measurement of 100 canes showed that the average growth from May 22 to 

 July 2 was approximately 1 inch per day, with Niagara and Fredonia making the 

 most rapid growth and Delaware the least. 



Sprays applied when the average cane growth was 4 inches or less prevented 

 most girdling, but when the growth between sprays was about 8 inches the number 

 of girdled canes was 8 to 15 percent greater than on the unsprayed vines. Cryolite 

 at the rate of 3 pounds in 100 gallons was more satisfactory than lead arsenate, 

 which caused some foliage injury when c -mbined with sulfur or copper oxide in 

 frequent applications. 



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



The Smaller European Elm Bark Beetle, Scolytus multistriatus Marsham. Elm 

 logs in Alford, reported by the owner to have been cut just prior to April 1941, 

 were found to contain only large larvae of Scolytus multistriatus at the end of 

 September. No emergence holes could be found. If the time of cutting was given 

 correctly, the size of the larvae present would suggest that one generation a year 

 may be common in this region of the Berkshires. Logs of both American elm, 

 Ulnius americana L., and slippery elm, Ulmus fulva Michx., were heavily infested. 

 In an adjacent area, elm logs reported by the owner to have been cut at various 

 times from the early spring through late fall of 1941 showed the presence of brood 

 galleries in all stages of construction. Completed brood galleries containing large 

 larvae, galleries with small larvae, and incomplete galleries with only eggs and 

 active parent beetles were found. 



The Native Elm Bark Beetle, Hylurgopinus rufipes (Eich.). At the end of 

 September 1941, other elm logs in Alford which were reported by the owner to 

 have been cut just prior to April 1941 contained larvae, pupae, and young adults 

 of H. rufipes and many emergence holes. These logs were adjacent to those cut 

 at the same time which were infested with 5. multistriatus. The evidence suggests 

 that in this vicinity H. rufipes beetles which develop from the first eggs laid in 

 the spring may complete their development sooner than S. multistriatus beetles. 



Insects Observed in the First Tree in Massachusetts Found to have Dutch 

 Elm Disease. (W. B. Becker.) Numerous feeding or overwintering tunnels 

 of H. rufipes were observed in the tree, especially near the base. Adult beetles 

 were active in these tunnels in mid-September. Such tunnels, of course, are com- 

 monly encountered in live elm trees. No correlation was determined between the 

 occurrence of these tunnels and the presence of the fungus, Ceratostomella ulmi 

 (Schwarz) Buisman, in any part of the tree. 



Scouting for Elm Bark Beetles. (W. B. Becker.) Brief scouting revealed the 

 presence of Scolytus multistriatus at three locations new to this office: Concord, 

 Alford, and Hancock, Mass. 



At Alford, in the vicinity of the first tree in Massachusetts found to have Dutch 

 elm disease, this beetle was abundant in elm logs on an area being cut over for 

 cordwood. Hylurgopinus rufipes was also abundant in the vicinity of the diseased 

 tree. 



The Effects of Solar Heat on the Subcortical Development of the Native 

 Elm Bark Beetle, Hylurgopinus rufipes (Eich.) at Amherst. (VV. B. Becker.) 

 Laboratory and field work on this problem was continued. 



Insect Pests of Wood and Shade, Forest, and Ornamental Trees in Massa- 

 chusetts. (W. B. Becker.) Three hundred and one inquiries were received about 

 such insect pests. Eighty-four different kinds of insects were involved. Ants, 

 powder post beetles, termites, spruce gall aphids, elm leaf beetles, and secondary 

 tree-boring insects were received most frequently. 



