32 



4 inches wide. One man can operate the machine, stopping occasionally 

 to replenish the pressure by pumping. 



In using the torch, all trash and mulch in a circular area some five 

 feet in diameter about the trunk of the tree was burned clean to the 

 dirt. The time required varied with the density and moisture content 

 of the covering. Unless the sod and mulch is especially heavy, effective 

 work can be done in ten to fifteen minutes per tree, but if the sod is 

 very heavy and of long standing, and particularly if it is damp, as much 

 as half an hour will be required for each tree. 



Four tests were made : two in the Braden orchard at Olney, 111. ; 

 one in the Tanner orchard at Flora, 111. ; and one in the Vergon orchard 

 at Delaware, O. The following table gives the results obtained in the 

 first three tests. 



Further proof that the burning had a marked effect in reducing the 

 number of weevils is seen by contrasting the numbers of mined leaves 

 in the burned and unburned sections the following spring. In the or- 

 chard treated at Olney in the winter of 1919-20, 70 per cent, of the 

 leaves in the unburned part and only 34 per cent, of the leaves in the 

 burned area showed larval mines the following spring. At Flora, 28 

 per cent, of the leaves showed larval mines in the unburned area and 

 14 per cent, in the burned area. 



From examinations made in the Flora orchard at frequent inter- 

 vals from the time when the beetles started out of their winter quarters 

 in spring it was evident that there had been considerable migration of 

 the insects from the unburned to the burned area. 



The fourth test of the blow torch for burning the weevil in hiber- 

 nation was made at Delaware, O., in the old Vergon orchard, the same 

 type of kerosene torch being used as in the Illinois work. This orchard 

 it will be recalled, had been in grass for many years. Since the lower 

 hmbs of the trees had been killed or so weakened by the flea-weevils 

 that they were of little value, they had been removed and the heavj' 

 blue-grass sod had become established quite up to the trunks of the 

 trees. Under this condition we found burning difficult, since, if the 

 sod was dampened by rain or snow, at least 30 minutes, and sometimes 

 longer, were required to burn over a circular area five or six feet in 

 diameter, and even after burning for that length of time we occasion- 

 ally found live weevils within the burned area. Moreover, as shown 

 before, all the weevils were not hibernating within the burned area, 

 but many were in the sod between the tree rows as well as under the 

 spread of the branches, hence it is easily understood why no apparent 

 diminution could be seen the following spring in the bunied as com- 

 pared with the unburned area of this orchard. In this instance, there- 

 fore, we were forced to conclude that burning was of little practical 

 value. 



Sumtitary on burning in hibernation. — Our experience with this 

 kind of control leads us to believe that surface burning without the 



