maxillulae

The maxillula is a component of the mouthparts found in certain arthropods, specifically crustaceans and insects. In crustaceans, it refers to either member of the first pair of maxillae. For insects, the maxillula represents appendages that may be homologous to those found in crustaceans.1

In insects, the mouthparts are derived from modified appendages of the head segments. Typically, insect mouthparts include mandibles (jaws), first maxillae, and second maxillae fused to form the labium. The first maxillae, in particular, are complex structures that can bear sensory appendages called palpi. In some insects, like moths and butterflies, parts of the first maxillae are elongated to form a proboscis for sucking liquids. In other insects, such as heteropterans (true bugs), the maxillae are modified into stylets that, along with modified mandibles, form piercing-sucking mouthparts.234