46 MASS. EXPERIMENT STATION BULLETIN 157. 



the house was again cleared, and the plants, apparently perfect!}' clean, 

 removed to the garden. In late summer, however, Mr. Holden found the 

 plants infested, and during the following fall and winter (1912-13) the 

 insect was again present in troublesome numbers in his greenliouse. 



How is the absence of the fly during the fall of 1911 and winter of 1912 

 to be accounted for? As there are no other greenliouses in Mr. Holden's 

 vicinity, it could not have passed the winter actively in a neighboring 

 greenhouse. Unless, then, as is possible, it passed the winter in some 

 near-by dwelling house, where some one of its food plants was kept for or- 

 namental purposes, as occasionally happens, hibernation is the only 

 rational explanation that remains. 



CONTROL. 

 Picking of Leaves. 



Until recently the picking and destruction of the infested leaves was 

 the only means known for the control of this insect. This method, how- 

 ever, aside from other disadvantages, has not proven effective in all cases. 

 Mr. Walker Holden has had fairly good success with it in the case of white 

 marguerites, but it was utterly ineffective in the case of yellow marguerites, 

 and it rendered the feverfews unsalable. It is quite probable, also, that 

 he would have experienced more difficulty in connection with the white 

 marguerites had he not had in the house at the same time yeUow margue- 

 rites and feverfews, of which plants the flies are very fond. But aside from 

 the consideration of effectiveness, it is obvious that as a means of control 

 the method is by itself unsatisfactorj^ in cases where plants are gro'WTi in 

 quantity and time is valuable. Moreover, the loss of leaves is not to the 

 advantage of the plant. 



Spraying. 



" Black Leaf 40." 

 It was the intention of the \\Titer to discover, in connection with his 

 other studies of the pest, a more effective method of control. But before 

 the experiments along these lines were begun, a note entitled "A Remedy 

 for Chrysanthemum Leaf Miner," in the "Journal of Economic Ento- 

 mology " for December, 1912, b}'- J. G. Sanders of the College of Agri- 

 culture, INIadison, Wis., came to liis notice. In tliis note Mr. Sanders 

 says in part, as f oUows : — 



While experimenting with contact insectides for tlieir control, the nicotine 

 solutions, especially "Black Leaf 40," used as a spray with or without whale-oil 

 soap solution, proved a complete and satisfactory control. One part of nicotine 

 in 400 parts of water killed the eggs and larvae readily, as well as the newly formed 

 pupse. The pup« of all ages were killed with ^Jj nicotine solution. 



Mr. Sanders having discovered an effective remedy, the writer thought 

 it superfluous to experiment further along original fines; nor, again, did 

 the time available make it conA'enient for him to do so. His o^^^l experi- 



