34 First Report on Economic Zoology. 



Eesult. Every Apliis killed, also slugs, flies, wasps and butter- 

 flies. Xot a petal or leaf injured. Cost 5fZ. Journal S. E. Agric. 

 College. 



The quantities given first are, however, now found most successful. 



White Grubs or Maggots {Phorhia hrassicce, Bouclie) 

 causing great damage amongst Cabbages, 

 Carrots and Broccoli. 



The larvae and puparia of the Cabbage Eoot Fly {Phorhia hrassicce) 

 were reported to the Board of Agriculture from Castle Croft, near 

 Wolverhampton, as doing considerable harm. Several other corre- 

 spondents reported the same pest. The different reports sent out 

 are here united. This fly is a great pest in most cabbage-growing 

 districts in Great Britain, and also causes endless harm in North 

 America. 



The only publication of value on this pest is by Professor Slinger- 

 land, of Cornell University Agricultural Experiment Station. (" The 

 Cabbage Eoot Maggot, etc.," Bull. 78, Cornell Univ. Exp. Station, 

 Nov., 1894.) 



The flies, which are very like the house-fly, appear all the 

 summer in successive broods. Maggots may be found as late as 

 November. These latter pupate in the soil, but apparently some of 

 the adults also hibernate and come out and lay their eggs in the 

 spring. Generally there are three broods in Great Britain, and 

 undoubtedly the majority pass the winter in the puparium stage 

 either in the ground or in the heaps of cabbage stumps and roots one 

 sees so frequently on the farm. 



Prevention and Teeatment. 



The results obtained from a long series of experiments conducted 

 by Professor Slingerland seem to show that only two things can be 

 done to mitigate the evil caused by the Eoot Maggot. As a pre- 

 ventive the only effective device is to apply around each plant, 

 when it is set out, a disc made of tarred paper or card. These can be 

 cut out by machinery in large numbers, and as placing them around 

 each plant before it is set takes so little time the plan has been 

 adopted on a large scale by many American growers. 



A plan of the card disc invented by Mr. Goff is given on page 35, 

 This disc (A) must lie flat on the surface of the soil to stop the 

 flies from crawling beneath. 



