CHRYSANTHEMUM MIDGE. 91 
fish-oil soap will kill the adult almost immediately after emergence, 
if the spray is applied not more than three or four days previously. 
A separate sash house was erected closely adjoming the greenhouse 
in which the spraying was done. Here 100 plants were fumigated 
nightly for approximately eight weeks, tobacco paper at the rate of 1 
sheet to every 650 cubic feet of space being used. While some burning 
resulted, the midge was held in check. From these two experiments 
it is evident that either practice would be efficient. 
A large commercial grower in Indiana reports that following in- 
structions of this bureau he entirely eliminated the midge from his 
houses by fumigating with tobacco papers every night from December 
20, 1917, to March 20, 1918. 
Experiments conducted in several greenhouses in the District of 
Columbia in 1919 have indicated that consistent nightly fumigation 
is very effective in keeping down this insect. In several places where 
this was not advisable an effective spray was applied, consisting of 
nicotine sulphate (1-800) plus soap (one-half ounce to 1 ounce to 
each gallon of solution). 
SUMMARY OF CONTROL AND RECOMMENDATIONS. 
From the life history, as well as from the experimental data thus 
far submitted, it is clear that certain points must be kept in mind 
if the best practical results are to be secured. First, several genera- 
tions are always present in greenhouses during the spring and fall 
occurrences ; second, the adults emerge and mate during the very early 
morning hours, and egg laying quickly follows; third, preliminary 
control experiments show that the egg stage may be controlled by 
means of spraying or dipping the cuttings or plants; fourth, it has 
been demonstrated that the adult can be killed easily at the time of 
emergence by consistent spraying; fifth, fumigation experiments 
in a commercial house proved that the adult is easily killed by fumi- 
gation either with nicotine papers or hydrocyanic-acid gas; sixth, 
experiments applicable to general propagation practices show con- 
clusively that such measures offer a reasonable safeguard and pro- 
tection against doubtful stock and infested material without injury 
to the plants. 
By adherence to a definite control program, involving any of the 
above cited measures, either singly or in combination, the insect 
can be readily controlled. 
In case of a very light infestation daily picking of gall-infested 
leaves will hold the pest in check. Should this practice prove ineffec- 
tive, nightly fumigation for a period of two or three weeks may be 
resorted to. 
