DIPTERA OR TRUE FLIES. 



249 



3 and 4) ; but they do not come right out until they are ready 

 to pupate, when they leave the tunnels and metamorphose in 

 the ground. The brown sausage-shaped puparia (5 and 6) are 

 long and cylindrical and somewhat wrinkled ; from the pupa 

 inside the fly hatches in about three weeks. There are several 

 generations in the year —at least three according to my observa- 

 tions. The grubs may be found at all times, from May until 

 the carrots are lifted. When " rusted " the carrot leaves turn 

 prematurely yellow and red, and thus clearly indicate the 

 presence of P. rosa'. These flies are undoubtedly attracted to 

 the young carrots by their smell, as we find in Onion Fly, 



Fig. 142. — Carrot Plv (Psila rosce). 



1 and 2, Larva, nat. size, and may. ; 4, rusty carrot ; 3, enclosed larva ; 5 and 6, pu- 

 parium, nat. size, and mag. ; 7 and 8, imago, njit. size, and inag. 



Turnip Flea, &c. It is especially after thinning that the carrots 

 get blighted, and this for two reasons — first, we bruise the 

 plants in thinning them, and thus release the smell ; and 

 secondly, by loosening the earth around we expose the carrots 

 more readily to the fly. We should remember in all these pests 

 that the eggs must be laid on or very near the plant, as the 

 young larvae cannot travel far. 



Prevention and Remedies. — When thinning is necessary, we 

 should broadcast over the plants sand or ash in which a small 

 quantity of paraffin has been mixed, about a pint to a bushel 

 of sand. This destroys the smell, fills in the crevices, and 



