176 THE PLUM CUKCTJLIO. 
Considering the several records of jarring on peach given above, 
it would appear that this practice, on the whole, is not warranted 
from the benefits derived. Notwithstanding the large total of 
beetles caught in the course of the Barnesville experiment, averaging 
20.81 per tree, there was a lessening of infestation of only about 10 
per cent, as compared with the check. In the other instances, 
where the insects were less abundant, the difference is inconsequential. 
It is, however, a firmly established belief that jarring has been of 
the greatest value in protecting the plum crop, though no exact 
data have been given, and the inference possibly follows the fact of 
capture of the beetles in considerable numbers. It is regretted 
that there has been no opportunit3 r to try jarring on plums. In 
jarring for peachee, furthermore, quite a number of the fruit is 
almost unavoidably knocked off, a considerable proportion of which 
is sound. When there is an abundance or excess of fruit, this is 
beneficial; but when the crop is light, there is an important loss 
of fruit. In the Siloam Springs work, in 1908, a total of 1,610 peaches 
was knocked off during the season from the 9 trees, of which 4 only 
were infested. 
CULTIVATION FOR DESTRUCTION OF PUP2E. 
As has been shown elsewhere (p. 87), practically all of the larvae 
of the plum curculio pupate less than 3 inches below the surface of the 
soil. Over 92 per cent pupate within 2 inches and 63 per cent within 1 
inch of the surface of the ground. The pupa? of the curculio, in com- 
mon with those of many other insects, are extremely tender and are 
readily killed or injured by disturbance of the soil. It is probable 
that the mere breaking of the pupal cell, leaving the earth in contact 
with the body of the pupa, would be fatal to many, while others are 
undoubtedly killed by the crushing action of the earth. Superficial 
tillage of orchards when the pupa? are in the ground in maximum 
numbers should therefore serve greatly to reduce their number for the 
following season, and tillage during this season is extremely desirable 
as a part of proper orchard management. Pupa? not actually killed 
are exposed to the elements and are subject to the attacks of preda- 
ceous enemies, as ants, bird, etc. Sunlight appears to be quickly 
fatal to them and, as stated by Crandall, exposure to the air on a 
warm day in the shade will result in then death in a few hours. 
Extended observations on the life history of the curculio from various 
localities (p. 64) indicate that the insect is in the pupal condition in 
the ground for any locality in from 50 to 65 days after the falling of 
the blossoms of such fruit as the peach and plum. Data have also 
been presented to show that the minimum time spent in the 
ground is about 20 days, though the actual period of pupation is less. 
