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Morphology

Hymenoptera are divided into two suborders: Symphita and Apocrita.

The Apocrita are characterized by a constriction between the thorax and the abdomen. They are split into two groups:

• the Terebrantia which possess an ovipositor, most often visible.
• the Aculeata whose adult antennae comprise a maximum of 13 segments and  the female stinger replaces the ovipositor. The Crabronidae belong to this group.

Crabronidae are distinguished from Apidae (bees) by a glabrous body and the first tarsus of the third pair of legs elongate and cylindrical (widened and flattened in the Apidae).

Philanthus triangulum

Biology and behavior

The females catch their prey for their own food, paralyzing them using their stinger and storing them in a nest they have already constructed and prepared. Distinction is made between species according to where they live: ground-dwelling, which make their nest in the ground (the most common); caulicolous which nest in stems of plants with dry pith (medulla); and xylicolous, in dead wood. Some species finally build their nest by making mortar. The egg is laid on the paralyzed prey so that the larva has a ready supply as soon as hatching occurs. These prey are to be found from among numerous orders of insects, more rarely spiders.

Early on, the diverse phases of behavior (nest building, capture method, prey paralysis, transport, orientation and so on) inspired the interest of entomologists such as Réaumur and Fabre who made it an experimental ethological model for instinctive types of behavior.

Tripoxylon figulus

Crabronidae aphid predators

The Crabronidae are divided into 7 subfamilies. Among these are the Pemphredoninae which consist of about 30 species of aphid predator themselves spread over 6 genera : Pemphredon, Diotontus, Passaloecus, Polemistus, Sigmus and Psenulus.

Les Crabronidae se distinguent des Apidae (abeille) par un corps glabre et le premier tarse de la troisième paire de pattes allongé et cylindrique (élargi et aplati chez les Apidae).

Bembex rostrata