ee eee 
EES SS Se Se 
SSS 
oo — 
46 BULLETIN 1857, U. S. DEPARTMENT OF AGRICULTURE 
least 95 per cent of all beetles above ground. Fumigation with 
vaporized nicotine did not kill the adults. 
The effectiveness of hand picking the beetles, as practiced by many 
florists, may be counteracted by the overlapping of generations of 
this insect. It is therefore evident that to be successful hand picking | 
must be done very thoroughly and persistently. 
A modification of hand picking, wherein kerosene nicotine oleate 
was used to film the surface of the pools and puddles in heavily — 
watered beds, killed any beetles which came in contact with the in- 
secticide while struggling in the water. 
Cleanliness was practiced persistently in one greenhouse and was — 
of material assistance in reducing a heavy infestation. Immediately 
after cutting back the plants many adults in the soil and débris — 
were destroyed by scraping and removing a layer of surface soil to — 
a depth of about 2 inches, and then treating it to kill them. 
Treatments of the soil with the following insecticides either failed 
to kill the larve and pup or were detrimental to the plants: 
Acid phosphate. Lye (sodium hydroxide). 
Borax. Nicotine sulphate solution. 
Carbon disulphide. Orthodichlorobenzene. 
Hydrated lime. Paradichlorobenzene. 
Kerosene nicotine oleate. Sodium cyanide solution. 
Contact with tobacco dust, which was placed on the soil surface, — 
killed newly hatched larve, and the leaching of tobacco dust and © 
wood ashes also killed some larve and pupz in the soil. 
RECOMMENDATIONS FOR CONTROL 
A successful control program entails a combination of several © 
measures, since no single practice will suffice. In order to be effective 
such measures must be persistently followed and applied in such a 
manner that they will not conflict with the normal cultural program 
and conditions under which roses are grown. 
During the summer months the protection of the plants from im- | 
-mediate as well as future injury is the paramount consideration. © 
This may be accomplished by fumigating with hydrocyanic-acid gas © 
during the drying-off period to kill as many adults as possible, and © 
by scraping the surface soil from the beds when the plants are cut — 
back, and then spraying them with lead arsenate or calcium arsenate, 
using 4 pounds to 50 gallons of water, to protect the swelling buds 
from the further depredations of the beetles. 
From September to December eradication of the beetles should | 
be the florists’ aim, because they are still emerging and continue to 
feed voraciously for some time. Every effort should therefore | 
be directed toward ridding the houses of as many of the over- 
wintering beetles as possible in order to prevent a recurrence of an — 
infestation the following spring. During this period dusting must 
be very thorough and continuous, in order that the foliage may be 
kept coated with the poison. Hydrocyanic-acid gas, however, can 
not be used at this time at a killing strength without causing severe 
injury to the plants. Two or more treatments by filming the sur- 
face water of the bed with kerosene nicotine oleate may then be most 
effectively used to kill many adults. Beginning about the middle of 
a) 
| 
ae || 
i 
period of the plants consistently produced an average mortality of at 
i 
— 
. e 
| 
a | 
| 
| 
: 
i 
