48 MASS. EXPERIMENT STATION BULLETIN 327 



white light (daylight blue.) The bulbs were alternated at each examination 

 so that any difference in attractiveness of colors would not be influenced by 

 location. On the first night the lights were lit from dark until midnight, but 

 thereafter they were lit throughout the night. Observations were made once 

 each week. 



In the period between April 18 and May 29 while the lights were in operation, 

 801 moths, or 58 percent of the total, were collected in the trap with the clear 

 white bulb; while the trap containing the daylight blue bulb attracted 576 

 moths, or 42 percent of the total collection. 



In addition to the leaf roller moths, a large number of Dascyllid beetles of 

 the genus Ptilodactyla were collected in the traps. These beetles were identified 

 by two different authorities as P. serricollis Say and P. exotica Chp., but no 

 evidence that they were seriously damaging the roses was observed. 



During the summer of 1935 the orchard light trap experiment, begun in 1934 

 in the Bay Road orchard in South Amherst, was continued with the New Eng- 

 land Rural Electrification Committee and the Western Massachusetts Counties' 

 Electric Light and Power Company again cooperating with the Massachusetts 

 Agricultural Experiment Station. The work was made possible through support 

 of personnel by ERA funds. Eight light traps were used in the same location 

 as last year. 



The primary purpose, codling moth control, was again pursued in order that 

 comparison might be made 'with last years results. However, the develop- 

 ment and activity of other pests, as well as beneficial and harmless insects were 

 followed since each insect caught was counted and classified. Beginning August 

 1, new lights of different colors were tested and compared. 



The efficiency of the water-pan traps was increased in two ways: (1) by 

 placing a film of oil on the water in the pans, and (2 ) by raising the bulbs ap- 

 proximately 5 inches higher than last year so that the lower parts of the trees 

 were lighted as well as the upper. In 1934 the water-pan traps caught 20 per- 

 cent of the total whereas in 1935 they caught 37 percent, an increase of 85 

 percent. This increase apparently resulted from the changes mentioned above. 



In order to check the relative efficiency of the four electrocutor traps the 

 following method was used. For a period of 10 days, July 12 through July 22, 

 the electrocutor traps caught the following numbers of insects: No. 1, 3576; 

 No. 2, 2,122; No. 3, 3,350; No. 4, 3,822. Using the average catch per trap, 

 3,216.5, as a standard (equalling 100), the indices for the four traps are: No. 

 1,111; No. 2, 66; No. 3, 78; No. 4, 118. By the same method, the indices for 

 the water-pan traps are No. 1, 132; No. 2, 72; No. 3, 78: No. 4, 117. From 

 these figures it is evident that the outside traps, i.e., the end traps, caught a 

 far larger number than those between, indicating the advisability, where the 

 traps are to be used on a commercial basis, of placing them in every other tree, 

 at least. 



Until August 1, the work for 1935 was similar to that of 1934 and the data 

 secured will be used for checking and comparing with the data secured during 

 1934. During August, lights of different intensities and colors were used, but 

 since these colors are the components of natural white light, their combined 

 catches may be used as part of the year's catch for comparison with the previous 

 year's total. 



A comparison of the numbers of some of the most important groups and 

 species caught in the two years is given in the following table: 



