108 
The Cabbage Root-maggot 
Phorbia brassiccc Bouche 
(Pegomyia brassicce, AntJioniyia brassiccc) 
One of the most destructive enemies of cabbage and cauliflower 
in Illinois is the cabbage root-maggot. It is white or cream colored, 
resembling the onion-maggot (Fig. 26), which is known to all Illi- 
nois gardeners. It is one of the immature stages of a fly which is 
much like the house-fly in appearance, but more cylindrical, some- 
what smaller, and of a grayish or brownish color. The winter may be 
passed in either the adult, puparium, or maggot stage, the flies hiber- 
nating in rubbish, buildings, or any accessible place that will afford 
shelter, the puparia in onion bulbs left in the fields in the soil, and the 
maggots in the refuse bulbs. Early in spring the flies deposit their 
small, elliptical white eggs in small cracks and crevices near the 
stem of the plant, or on the stem beneath the surface. Usually 
within a week — not so soon if the weather is cool, but often within 
24 or 36 hours in the warmer parts of the year — small maggots 
hatch from the eggs, and immediately go into the ground and begin 
to feed on the roots or stalk. Becoming full grown in a few weeks, 
they leave the roots to pupate in the soil near by. They remain in 
this dormant stage, as oval brown pu])aria, for about two weeks (in 
summer), and from these the adult flies emerge. There may be two 
or more generations in Illinois, according to the length of the season. 
Most of the injury to cabbage and cauliflower by this maggot is 
done while the plants are small, and particularly to early cabbage. 
For this reason the acreage of early cabbage has greatly decreased 
in this state within the last few years. 
Bconoiuic Conti-ol. — Many methods have been recommended by 
various writers for the control of the cabbage root-maggot, but most 
of these are preventive rather than remedial. Cabbage seldom 
brings a high price, and many measures that have been proposed 
are impracticable because of their cost. 
For the prci'cntion of iiiac/gof attack in seed beds, probably the 
most successful and practical method of protecting the young plants 
is that of screening them, as suggested by Dr. James Fletcher,* and 
later successfully demonstrated on a large scale by Mr. W. J. 
Schoene.f This consists in growing the seedlings under cheap 
frames, made of light wood and covered with cheese-cloth (Fig. 6). 
to protect the plants from the cabbage-maggot flies. In Mr. 
Schoene's experiments it proved very successful. He savs : "Plants 
*Insects Injurious to Grain and Fodder Crops, Root Crops, and Vegetables. 
Bull. Central E.xperimental Farms, Ottawa, Canada, No. 52 (June, 1905), p. 35. 
tScreenings for the Protection of Cabbage Seed Beds. Bull. N. Y. Agr. Ex- 
per. Station. No. 301 (March, 1908). Geneva. 
