The Bembicini, or Sand wasps, are a large tribe

Tribe (biology)

In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...

 of crabronid

Crabronidae

Crabronidae is a large family of wasps, that includes nearly all of the species formerly comprising the now-defunct superfamily Sphecoidea. It collectively includes well over 200 genera, containing well over 9000 species. Crabronids were originally a part of Sphecidae, but the latter name is now...

 wasp

Wasp

The term wasp is typically defined as any insect of the order Hymenoptera and suborder Apocrita that is neither a bee nor an ant. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their...

s, comprising 20 genera

Genera

Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...

. Bembicines are predators on various groups of insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s. The type of prey captured tends to be rather consistent within each genus, with flies (Diptera

Diptera

Diptera , or true flies, is the order of insects possessing only a single pair of wings on the mesothorax; the metathorax bears a pair of drumstick like structures called the halteres, the remnants of the hind wings. It is a large order, containing an estimated 240,000 species, although under half...

) being the most common type of prey taken. Nests are typically short, simple burrows, with a single enlarged chamber at the bottom which is stocked with prey items for the developing wasp larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

; the egg may sometimes be laid before the chamber is completely stocked. It is common for numerous females to excavate nests within a small area where the soil is suitable, creating large and sometimes very dense nesting aggregations. Such aggregations tend to attract various species of parasitic

Parasitism

Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

 flies and wasps, many of which are cleptoparasites; in some cases, the sand wasps will prey on their own parasites, a surprisingly rare phenomenon in the animal kingdom. Although sand wasps are normally yellow and black, some sand wasps are black and white with bright green eyes.