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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
progress of the life history studies and experimental control measures. 
The following account is a summary of the results of the control measures 
which have been employed in commercial greenhouses and which 
proved effective. 
It is thought desirable to review briefly the seasonal and life history 
of the insect under greenhouse conditions. The duration of the several 
stages are as follows: The egg stage varies from 7 to 15 days, the.larva 
from 35 to 60 days, the pupa from 8 to 13 days, and the adult from 
about 70 to 100 days or more. One female lived for 364 days after 
emergence. During the winter months the adults remain in hiding in 
dead leaves or in the mulch and are seen only occasionally. About the 
middle of February they can be found more frequently feeding on the 
plants. 
Egg laying commences about the first of March and continues through 
April and in some cases May and June. The larva and pupa stages are 
spent in the soil where the larvae feed on the roots of the plants. The 
first individuals of the new brood of adults begin to appear in May and 
because of the long period of egg-laying the number of beetles steadily 
increases, reaching its maximum in June and July. Soon after their 
emergence these adults deposit eggs and a second brood appears in 
September and October, the adults of which, however, do not lay eggs 
until the following spring. They feed voraciously for a time and then 
conceal themselves until the following February, occasionally coming 
out on warm clear days during the winter and feed to some extent on 
the green foliage. 
Before discussing control measures carried out in individual establish¬ 
ments, mention should be made of the fact that it is a practice among 
rose growers to replace the plants and soil at intervals of several years. 
Without doubt this operation results in ridding a house of the insects 
provided it is done thoroughly and no beds are allowed to remain as 
sources of infestation. In the subsequent experiments to be discussed, 
the removal of plants and soil helped materially in reducing the severity 
of the infestation. 
Investigation of the reported infestation at Alexandria, Va., in 1919 
revealed the seriousness of the injury and the necessity for drastic 
control measures. Fumigation with hydrocyanic-acid gas using 2 
ounces of sodium cyanid to each 1,000 cubic feet of space with an ex¬ 
posure to the gas lasting two hours, resulted in a 97 per cent mortality 
of all beetles above ground. The plants had been sprayed with arsenicals 
so that the surviving beetles found little green foliage to feed upon. 
