An in-depth description of head morphology and mouthparts in larvae of the black soldier fly Hermetia illucens

The larvae of the black soldier fly (BSF) Hermetia illucens are increasingly being used for waste management purposes given their ability to grow on a wide range of organic decaying materials. Although significant efforts have been spent to improve the mass rearing of BSF larvae on specific substrates and their bioconversion capability, little is known about the biology of this insect, especially with regards to the digestive system. In this study, we analyzed the morphology of the head and buccal apparatus of H. illucens larvae by using optical and scanning electron microscopy, evaluating the different mouthparts and their modifications during larval development. Our analysis showed that the larval head of H. illucens presents similarities to those of campodeiform insect larvae, whereas the mandibular-maxillary complex represents a food intake solution typical of Stratiomyidae that enables BSF larvae to ingest semiliquid food. The mouthparts resemble a “tunnel boring machine”, where the hypopharynx separates finer organic particles from coarser and inorganic ones.