186 
have full play. This fact should be borne in mind in locating onion 
beds. 
The amount and kinds of manure used may have an important 
influence on the damage done by this insect. Prof. C. G. Hewitt, 
of the University of Manchester, England, has recently shown* 
that Anthomyia radkuni, a European species very closely related to 
the onion-maggot, breeds freely in horse manure. It has often been 
noticed by entomologists and gardeners that fields which have been 
abundantly manured are worse infested than those where little ma- 
nure has been used.f 
It is much easier to keep these maggots from infesting onions 
than to kill them after their appearance. The three best repellents 
and preventives which have been recommended from time to time 
are hellebore, tobacco dust, and dry lime. The first two are dis- 
cussed under remedies for the cabbage root-maggot, (pages 109 and 
no) and on pages 154 and 155. Dry lime may be applied in the 
same manner as tobacco dust. These substances either repel the 
fly or prevent the maggot from reaching the plant even tho the 
eggs are deposited. They should be applied about the time the 
plants are sprouting or just as they appear above ground. 
After plants have become infested it is often possible to kill 
the maggots before they enter the bulb by applying a contact in- 
secticide. Carbolic acid emulsion and a decoction of hellebore 
(pages 153, 154) have given the best results. They should be ap- 
plied as soon as the maggots are noticed, or at least before they 
enter the bulbs, otherwise it is impossible to reach them with any 
insecticide. 
Old onions may be used as traps for the maggots by placing 
them along the edges of the field in small piles in early spring, 
before the onion seed has been planted. The flies will be attracted 
to these decaying onions, which should be destroyed after infes- 
tation, particular care being taken to do this before any of the 
maggots have become adults. 
Mr. F. A. Sirrine:]: suggests the following hand method : "To 
get at the onion-maggot after the eggs have been laid, carefully 
lift all the infested onions and destroy the maggots by crushing 
or by dipping in kerosene. If this is done early in the season, 
when their work is first noticed, it will be no more of a task than 
the process of first weeding." 
*0n the Life-history of the Root Maggot. Anthomyia radicum, Meigen. 
Jour. Econom. Biol., Vol. II, Pt. 2 (Aug. 31. 1907), p. 57; and On the Bionom- 
ics of certain Calyptrate Muscidae and their Economic Significance, with es- 
pecial Reference to Flies inhabiting Houses. Ibid, Pt. 3 (Dec. 11, 1907), 
pp. 86-87. 
tFor tests with "blood and bone" sec page iii. 
JMaggots and Smut in Onions. Rural New Yorker, May 12, 1900, Vol. 59, 
P- 334- 
