112 
rotation of crops. It is known that the rose is the only plant 
attacked by the insect under discussion, consequently if the in¬ 
fested range is planted to some other crop—for example, carna¬ 
tions—for one year, roses may again be planted in the range 
without danger from the original infestation, provided, of course, 
that new and clean plants are used. During this one-year rota¬ 
tion it is absolutely necessary that not a single rose plant be 
grown in the entire range. If more than one range is infested, 
it is desirable to rotate all of them the same year; but if this is 
impracticable, the beginning, at least in Cook county, should be 
made with the ranges furthest south, for it is known that midges 
there usually spread in a northerly direction, the reason being, that 
the prevailing summer wind is from the south or southwest,— 
and, as before said, the wind is practically the only means of dis¬ 
semination, aside from transportation on infested plants. 
The other method, which may be used when it is undesirable 
to rotate, consists in thoro cleaning of the house in midwinter, 
this method having a decided disadvantage, however, since the 
winter crops are the most valuable, the highest prices usually 
prevailing at that time. The cleaning should be done in December 
or January, when the insects are dormant in the soil. The plants 
should be removed and destroyed, for pupae may remain in the 
soil among the roots. Likewise the earth should be removed from 
the benches and hauled away some distance from the houses, so 
that there will be no possible danger of reinfestation from this 
source should any of the pupae survive the winter out-of-doors. 
As a further precaution the rubbish beneath the benches should 
be removed, and the earth floors and the benches thoroly sprayed 
with some contact insecticide, such as 20 percent kerosene emul¬ 
sion. None of the living insects are likely to survive the fore¬ 
going painstaking procedure. It is hardly necessary to say that 
new soil and new clean plants must take the place of the old. 
Other directions, such as the cleaning of all infested houses at 
the same time, etc., as given above in the discussion of the rota¬ 
tion method, apply equally to the cleaning method. 
Such practices have been thought to be impracticable bv some 
florists not fully acquainted with the great damage done by this 
insect, but it is indisputable that the cost of such operations are 
inconsiderable when compared with the annual loss occasioned by 
this pest. 
Hydrocyanic acid gas has been tried as a remedy, but it is 
inefficient in controlling this maggot in greenhouses in summer. 
It kills the flies, but will not kill the maggots—partly because 
they are so well protected within the buds—unless used at a 
strength which will injure the plants. Further, the flies are con- 
