416 INSECT PESTS OF FARM, GARDEN AND ORCHARD 



does not seem to have been carefully observed, but from analogy 

 is probably somewhat similar to that o'f the cabbage root-maggot, 

 except that the maggots of the carrot rust-fly develop and trans- 

 form on carrots in storage if the temperature be sufficient. 



Control. Late sowing has been practiced to advantage, and 

 the rotation of crops is of obvious importance, as is the deep plow- 

 ing of infested land. Where carrots have been stored in earth, this 

 earth into which the larvse have entered and pupated should be 



FIG. 300. The carrot rust-fly (Psila rosae Fab.): d", male fly; 9 , female fly, 

 side view; a, antenna of male; b, full-grown larva from side; c, spiracles 

 of same; a, anal extremity from <he end; e, puparium; /, young larva; 

 g, anal segment from the side eight times natural size except a, c, d, g, 

 more enlarged. (After Chittenden, U. S. Dept. Agr.) 



treated, either by burying it deeply, spreading it out in thin layers 

 on the surface, or throwing it into pools where it will be frozen. 

 Kerosene emulsion, 1 part stock solution to 10 of water sprayed 

 along the rows while the carrots are young, or sand, land plaster 

 or ashes, to 3 gallons of which 1 pint of kerosene has been added, 

 sprinkled along the rows, have been of some value in Canada. 

 These should be applied three or four times, once a week after the 

 roots begin to form, and particularly after the rows have been 

 thinned. 



