The Currant Fruit Fly. 215 



The first lot of 150 fruit flies were set free on an island 

 during a moderate southwest wind which blew toward the com- 

 mercial currant and gooseberry garden. An examination of the 

 vegetation on this island showed the presence of a few wild 

 gooseberry bushes. As indicated in table 19, two marked females 

 were captured in this garden at a distance of 3290 feet from the 

 point of liberation. These specimens were forced to fly across 

 a bay of the Penobscot River, varying from 200-500 feet in 

 width. 



The second lot of 50 marked trypetids were released on the 

 side of a hill at an elevation of about 50 feet, during a light 

 southeast wind which blew directly away from the commercial 

 currant and gooseberry garden. Two marked females were cap- 

 tured in this garden at a distance of 2650 feet from the place of 

 liberation. The two adults were collected after 2 and 15 days of 

 freedom. These specimens may have been caught up by changes 

 of winds which carried them towards this currant and goose- 

 berry patch, or they may not have made a continuous flight but a 

 series of short flights which finally brought them into this gar- 

 den without the influence of the wind. 



The third lot of marked adults were freed on a level stretch 

 of country with no barriers, such as rivers or hills between the 

 point of liberation and the commercial currant and gooseberry 

 garden. At the time that the specimens were released, a light 

 northwest wind was blowing toward the garden. Within 12 davs 

 five marked fruit flies were captured in this garden at a distance 

 of 1115 feet from the place of liberation. 



In the last experiment we endeavored to determine whether 

 marked fruit flies when liberated in a gooseberry patch locate! 

 in a yard in the residential section would travel to the commercirjl 

 currant and gooseberry garden. This problem is a matter of 

 much concern economically, if control measures are adopted in 

 a non-isolated currant or gooseberry patch. Fifty marked 

 females were set free by placing the jar containing the specimens 

 on the sod in tall grass under a gooseberry bush. The flies 

 gained their freedom during a perfectly cah;: spell. Within 

 ten days eight marked specimens were captured in the commer- 

 cial currant and gooseberry garden at a distance of 300 feet from 

 the place of liberation. 



