April, ’20] WEIGEL AND CHAMBERS: STRAWBERRY ROOT-WORM 
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while others could be found lying on the surface of the bench soil and 
beneath the plants. Owing to the fact that the adults showed a marked 
tendency to feign death, a total of 317 of the apparently dead insects 
were collected and held in cages for several days for further observa¬ 
tions. Of these less than 3 per cent revived from the effects of the gas, 
or expressed in other words a killing of 97 per cent of the adult beetles 
resulted from the above fumigation. 
As was anticipated practically all of the tender growth was more or 
less burned. This injury, however, was only temporary since at the 
expiration of three weeks the plants were in excellent condition and 
had produced an abundance of newly forced growth which was attrib¬ 
uted to the stimulating effects generally following fumigation with 
hydrocyanic-acid gas. Incidentally the burning back of this young 
growth deprived the few remaining adults of their favorite place of 
feeding. 
From the above experiments it appears that until further progress 
has been made in life history studies and habits of this new rose pest in 
greenhouses, a satisfactory method of controlling the adults of the 
strawberry root-worm is by the use of hydrocyanic-acid gas, at the 
rate^of two ounces sodium cyanid per one thousand cubic feet of space, 
with an exposure of two hours. The destruction of the adults at this 
time should forestall a recurrence the following spring and summer, 
since a very large percentage of the adult females are killed many 
months prior to the normal time of egg laying. 
Mr. Alvah Peterson: This insect has been very injurious in a 
large rose-house at Summit, N. J., for three seasons. For two seasons 
we have been making more or less careful studies on the life history 
and control measure. We have found at least two generations during 
the year, the adults appearing in large numbers during the months of 
June and July, and again in September. At this time of the year 
(December) you will find the form in the soil passing the winter in 
the adult stage. About the first of February, the adults come out, 
feed and then deposit their eggs. They continue to deposit eggs 
until about the last of April, and a little later young larvae are found 
in the ground about the base of the rose plants. Full grown larvae 
and pupae are abundant early in June. The adults make their appear¬ 
ance in considerable numbers in June and July. During August the 
adults are greatly reduced in numbers. Again in September full 
grown larvae and pupae may be found in the soil and the pupae change 
into adults. So far as observed all of the adults come out and feed 
before going into a dormant condition. 
