34 First Report on Economic Zoology. 
Besult. Every Aphis killed, also slugs, flies, wasps and butter- 
flies. Not a petal or leaf injured. Cost 5 d. Journal S. E. Agric. 
College. 
The quantities given first are, however, now found most successful. 
White Grubs or Maggots ( Phorbia brassicce , Bouche) 
causing great damage amongst Cabbages, 
Carrots and Broccoli. 
The larvae and puparia of the Cabbage Boot Fly ( Pliorbia brassicce) 
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 Boot 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 Treatment. 
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 Boot 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. 
