ALFALFA WEEVIL. 11 
SUMMER FLIGHT OF THE ADULTS. 
The heat of the soil is also probably an important cause of that 
increase in the activity of the adults called the summer flight, which 
is greatest during the dry, hot weather beginning in June and end- 
ing in August. This flight accounts for the presence of many adults 
in grassy “places and orchards, where they alight and find protec- 
tion from the heat. It helps to restock fields in which the weevils 
have been killed and makes it necessary to repeat the treatment 
year after year, and on the borders of the infested district it con- 
tributes to the spread of the pest. The summer flight is not a gen- 
eral movement of the weevils from the fields to seek more suitable 
hibernation places elsewhere. There is no such movement, and 
virtually all of the weevils spend the winter in the fields. 
WORK OF THE LARV IN THE SECOND CROP. 
If no treatment is given the infested field after haying, the larve 
which have been feeding upon the first crop gather upon the buds 
of the stubble, and although many have been killed by the heat of 
the earth after the cutting, there are still enough to prevent the 
sprouting of the second crop for a time nearly equal to its usual 
period of growth. By that time most of them have finished their 
feeding and growth and have gone into the pupal stage, and there is 
consequently no attack upon the later growth. 
ACTIVITIES OF THE NEW GENERATION OF WEEVILS IN SUMMER AND FALL. 
At the time of cutting the second crop the fields are full of weevils 
of the new generation, and there are usually many more weevils in 
the second-crop hay, which is cut at this time, than in that of the 
first and third crops. Their activity is greater at night than by day, 
and this condition continues until the cool nights of September 
begin. As autumn progresses, they haunt the plants less and less 
and fortunately are nearly all on the ground before the thrashing of 
the seed begins. No live weevils have ever been found in alfalfa seed. 
About one-half of the females of the new generation of beetles 
are ready to deposit eggs by the middle of October, and egg laying, 
chiefly in dry stems, goes on for about a month after that time. 
Few of these eggs hatch before winter, and some of them hatch 
the following spring and probably take part in the early Bunce 
upon the first crop. 
These habits of the weevil and the relations between it and the 
crop, the climate, and the country, comprise most of the facts for 
which a practical use has been found. Upon them are based all 
effective plans for preventing its ravages and retarding its spread. 
RECOMMENDATIONS FOR THE CONTROL OF THE WEEVIL.’ 
SILTING. 
Weevils can be killed in late winter or early spring by irrigating 
the fields with very muddy flood water and so burying them under 
1 Jn the field tests of spring and fall cultivation and the dust-mulch treatment the Burean of Entomology 
has had the cooperation of the entomological department of the Utah experiment station. 
