M MASS. EXPERIMENT STATION BULLETIN 355 



Mr. W. E. Tomlinson of the Waltham Field Station cooperated by carrying on 

 some experiments with H. rufipes in Waltham. Elm logs cut in mid-April were 

 attacked for oviposition purposes in late April and early May. Adults of the next 

 generation began to emerge from the logs in early August. In early September 

 elm logs cut in mid-July were observed being attacked by adult beetles. Since 

 the experiment is not complete, It is not yet known whether brood galleries were 

 made or not. 



Mr. Tomlinson also carried on some experiments with Scolytus midtistriatus 

 in Waltham, a town within the area infested by these beetles. Adults were 

 •observed attacking a recently felled elm tree in small numbers in early May. 

 Adults of this same generation which started to attack some elm logs in the 

 vicinity at about the same time gave rise to a generation which began emerging 

 in early August. Elm logs cut in mid-July .and placed ne.xt to the above logs 

 from which the beetles were emerging, were first observed to be attacked by 

 adults in early August. Examination of this bark early in September showed the 

 presence of eggs and parent adults in brood galleries. This study indicates that 

 Scolytus muUistriatus may have one complete and a partial second generation 

 in the vicinity of Waltham. 



Insect Pests of Shade and Ornamental Trees. During the summer the campus 

 trees were examined for the presence of insect injury in order to form a basis for a 

 spray program for pest control. In the fall a survey was made of the efTects of 

 the hurricane on shade and ornamental trees on the campus. Although not 

 strictly entomological in nature, the survey pointed out some interesting en- 

 tomological problems. 



In addition to eleven species of insects infesting wood or wood products, 95 

 species of insects on 34 diflferent genera of shade and ornamental trees were sent 

 to the Shade Tree Laboratory for identification. 



A bulletin of an economic nature on the control of shade tree insects was pub- 

 lished (Mass. Agr. Expt. Sta. Bui. 353). 



Control of Red Spider on Greenhouse Plants. (W. D. Whitcomb and William 

 Garland, Waltham.) Further experiments with sprays containing extractives 

 from derris and cube indicate that effective sprays of this nature for combating 

 the common red spider, capable of giving 90-{- percent control consistently, should 

 contain .03 percent total extractives of which .0075 percent is rotenone. This is 

 equivalent to a stock mixture containing l}/2 percent rotenone and 4J^ percent 

 other resins, diluted 1-200. Sprays containing these active ingredients are slightly 

 more consistent in effectiveness if combined with brown camphor oil rather than 

 with soluble pine oil or sulfonated castor oil. The addition of .2 percent Karaya 

 gum increased the effectiveness about 5 percent, apparently by building up the 

 deposit on the leaves; but when both gum and spreader were added, the run-off 

 was increased and no benefit from the gum resulted. At 80° F. the effectiveness 

 against red spider was 25 to 40 percent greater than at 60° F. 



An alcoholic extract of derris containing .0075 percent rotenone and .0225 

 percent other extractives was 10 percent more effective than a similar extract 

 with .005 percent rotenone; and the addition of .005 percent pyrethrins not only 

 failed to increase the mortality to red spider but actually gave an average decrease 

 of 6 percent in three experiments. 



The addition of Karaya gum increased slightly the effectiveness of commercial 

 thiocyanate spray and a commercial selenium compound, but the greater run-off 

 resulting from the addition of a spreader consistently reduced the mortality to 

 red spider. Both of these materials were only moderately effective in single 

 applications but gave promising results when repeated in three or four appli- 

 cations. 



