Bean Weevil
These small (1/8") weevils feed on the leaves and pods of beans and peas. They become a problem when you harvest and store the dry beans. Eggs hatch on the bean and the larvae work their way inside and eat them.
Control
Practicing crop rotation is always a good preventative method.
If the beans are to be used as food you can kill any weevil eggs by heating the beans to 135 degrees F for several hours.
If you want beans for replanting you can treat them with diatomaceous earth.
Image: Frank Peairs, Colorado State University, Bugwood.org