Petiole (insect anatomy)

The petiole in insect anatomy refers to the narrow waist or stalk-like segment connecting the thorax and abdomen in certain insect groups, most notably in the order Hymenoptera (ants, bees, wasps). It represents one or more highly constricted abdominal segments (typically the first or second, or both) that allow for increased flexibility and mobility of the abdomen. This flexibility is crucial for tasks such as stinging, ovipositing, and manipulating objects. The petiole may consist of one node (a single swollen segment) or two nodes, depending on the species. The presence and form of the petiole are important taxonomic characters used in insect identification and classification, particularly within Hymenoptera. The portion of the abdomen located behind the petiole is called the gaster.