1-11. INSECTS AND RODENTS
The final major cause of food deterioration is insects and rodents.
a. Insects. Insects are particularly destructive to cereal grains and to fruits and
vegetables. Both in the field and in storage, it has been estimated that insects destroy 5
to 10 percent of the United States (US) grain crop annually. In some parts of the world, the
figure may be in excess of 50 percent.
(1) Opening for decay. The insect problem is not just one of how much an
insect can eat, but when insects eat, they damage the food and open it to bacteria,
yeast, and mold infection. A small insect hole in a melon, not so bad in itself, can result
in the total decay of the melon from bacterial invasion.
(2) Control by use of chemicals. Insects are generally controlled in grain,
dried fruits, and spices by fumigation with such chemicals as methyl bromide, ethylene
oxide, and propylene oxide. The use of these latter two fumigants frequently is
prohibited with foods high in moisture because of the possible formation of toxic
(3) Insect eggs. Insect eggs may persist or be laid in the food after
processing, as for example in flour.
b. Rodents. The problem with rodents is not only the quantity of food they
consume, but also the filth with which they contaminate foods. Rodents' urine and
droppings may harbor several kinds of disease-causing bacteria. Rodents can be
directly or indirectly involved in the transmission of such diseases as salmonellosis,
leptospirosis, and murine typhus. One rat pill, or fecal dropping, can contain several
million bacteria. Even if the pill does not get into food directly, it will become dry and fall
apart or be crushed. The particles then may be blown or carried into food.
c. Control of Insects and Rodents. Insects and rodents may be effectively
controlled by following three rules.
Keep insects and rodents out of facilities by pest-proofing the building.
Deprive pests of food and shelter by following good housekeeping
Use appropriate control measures to exterminate pests.