Secondary stress. A secondary stress is any stress in the structure which is not a primary stress or peak stress. Source: API SPEC 16R, Specification for Marine Drilling Riser Couplings, Exploration and Production Department, First Edition, January 1997. Global Standards.
Digger bees are sometimes classified in the family Anthophoridae along with the carpenter bees. These hairy bees range from 5 to 25 mm in length and, like other members of this family, the females use scopae (stiff hairs) to carry pollen. Most species nest in the ground or in vertical banks, often in sandy soil. Some species waterproof their brood cells with secreted waxy or oily material.
As one of the larger of the wasp species, these flying pests may seem quite threatening at first glance. There are many different subspecies, and with those come different appearances. The most common of the digger wasps are the great golden digger wasp and the blue digger wasp. The great golden digger has a bee-like appearance with gold or amber stripes along its thin torso, while the blue digger has a similar body type but a blue-metallic sheen.