1911] 



Morse — Lucilia sericata as a Household Pest 



91 



tion-room, and in the front of the hving-room. The rugs in the 

 bay-windows were the most popular, excepting the large one 

 in the hall, and it was at the front windows in the living and 

 reception rooms that the flies swarmed. 



"We are still finding three or four [flies] daily." 

 The flies, several of which were sent me, proved on examina- 

 tion by Mr. C. W. Johnson to be Lucilia sericata Meigen, a 

 common green-bottle fly. 



The accompanying plan and scale will make clear the relation 

 of chimney, rugs, and windows, and the direction and length 

 of the larval migration. The house faces nearly west. 



Fig. 1. X = fireplace of squirrel's chimney. The maggots were 

 most numerous under the oriental rugs in the front of 

 the hall and in the two bay windows at front of house. 



Judging from the data secured, the odor of the decaying carcass 

 of the squirrel, passing out of the top of the chimney, led to it 

 the female flies seeking suitable places to oviposit. The larvae 

 of Phormia regina, an allied species, have been observed by Folsom 

 to be negatively phototropic until maturity, when they become 

 positively phototropic for a brief period, seek the light, leaving 

 the food to travel to some distance; then, becoming negatively 

 phototropic again, they seek shelter in which to pupate. Appar- 

 ently, the larvae of Lucilia sericata exhibit similar tropisms. 

 This behavior, it is easy to see, is adaptive in character, resulting 

 in the development and preservation of larger numbers, under 

 natural conditions, than if the larvae remained in the food material. 



Although all of the larvae that could be found were destroyed, 

 it is evident from the abundance of the flies that many escaped 



