Stored-Grain Pests. 45 
have not been thoroughly cleaned. 
Wooden bins and wooden parti- 
tions in grain storehouses and in 
the holds of grain-carrying ships 
become the nesting places for an 
incredibly large number of grain 
pests. Certain of these can and do 
bore into the softer portions of the 
partitions and timbers that are 
used over and over again as dun- 
nage, and the excavations they 
make serve as hiding places not 
only for themselves but all other 
species associated with them. Un- 
less such bins and partitions are 
thoroughly disinfected by fumi- 
gants, these hidden insects can not 
Fig. 63.—Hymenopterous parasite of grain 
Adult parasite resting upon a 
kernel of wheat. These tiny guat-like 
insects are beneficial but their help 
pests. 
be killed. 
Larva of a kind of fly that 
Fic. 64. 
preys beetles and 
mites, This white threadlike 
worm is sometimes found in 
grain dust and attains a length 
of about three-fourths of an inch; 
while interesting, it is of no 
practical value. 
upon grain 
The mere spraying of 
contact insecticides upon the walls 
usually comes too late to prevent dam- 
age to the crop in which they are most 
abundant. 
will not reach them. If uninfested 
erain is placed in such bins, it natur- 
ally will become infested by the insects 
coming from the bin walls. 
Likewise, uninfested grain should 
not be placed for shipment in sacks 
previously used for grain storage, for, 
as shown in figure 32, these old sacks 
often harbor insects unless they have 
been treated by heat or fumigation. 
Certain extensive and costly infesta- 
tions have been traced directly to the 
use of secondhand untreated grain 
sacks. 
Grain stored in the open or in 
poorly constructed cribs or bins may 
become infested by insects flying in 
from outside sources. 
HOW TO PREVENT PRIMARY 
INFESTATION. 
Infestation of grain in the field 
can not be entirely prevented, but 
by proper precautions it can be re- 
duced to a minimum. ‘The first gen- 
