Petiole (insect anatomy)
In entomology, the term petiole is most commonly used to refer to the constricted first (and sometimes second) metasomal segment of members of the Hymenopteran suborder Apocrita; it may be used to refer to other insects with similar body shapes, where the metasomal base is constricted. It is occasionally called a pedicel, but, in entomology, that term is more correctly reserved for the second segment of the antenna. 
The term may also be used in the context of wing veins, where a wing cell that is ordinarily four-sided is reduced to a triangle with a stalk (the cell thus being petiolate).
The stalk at the base of paper wasp nests is also called a petiole.