THE BEO AD-BEAN WEEVIL. 17 
2. A 24-hour exposure gave only about 2 per cent better results 
than one of 18 hours. 
3. A 48-hour exposure gave about a 5 per cent better result than 
one of 24 hours. 
4. Seven pounds to 1,000 cubic feet for 24 hours was the least 
amount to give a 100 per cent killing. 
5. Germination is not affected by the treatment, as beans treated 
with 15 and 20 pounds per 1,000 feet for 24 hours gave 95 and 97 per 
cent germination. 
Contrary to expectations, it was found that fumigating while the 
insects were in the larval stage was less effective than in the adult 
stage. A glance at Table XII will show that when the first fumiga- 
tion took place in August, almost 40 per cent of the larvae were not 
full grown. These were still eating within the bean, and had not 
come up to the epidermis and formed the " window " through which 
the adult emerges. It is evident, therefore, that the gas can not pene- 
trate into the interior of the beans to the partially grown larvae as 
easily as it can reach the full-grown larvae, pupae, or adults directly 
under the skin. 
It was further observed that in the beans fumigated in August a 
number of full-grown larvae and pupae had been killed. 
Lengthening the time of exposure did not greatly increase the 
percentage killed. This conforms to the opinions of Dr. W. E. 
Hinds (6) of the Alabama Experiment Station, who says, "As a 
matter of fact, most, if not all, of the killing will have occurred 
during the first 6 hours of the exposure, and the building may be 
ventilated after that time, as a minimum, has elapsed, although it is 
better to wait 12 hours or longer." On the effect of carbon disul- 
phid on the germination of the seeds, Dr. Hinds states : " It would 
appear from numerous tests that there is practically no danger of 
injuring germination in treating seeds that are well matured and 
dried out before treatment is given. It would not he wise to treat 
moist seeds, or planting seed of any kind, during periods of very 
humid atmosphere, as the seeds might take up enough moisture to 
make them liable to injury from the vapor." 
HOLDING OVER SEED. 
Life-history studies showed that the horse-bean weevil had but 
one generation a year, that it did not breed in the dry beans, and 
that the last few remaining live adults died by the 1st of July. 
By merely holding the beans over, therefore, until the second year, 
they will be uninfested as far as live weevils are concerned. The 
beans should be stored in sacks or containers tight enough to pre- 
vent any live weevils getting out during the first season. 
