Anatomy and histology of the alimentary tract of the female of the biting midgeculicoides nubeculosusMeigen (Diptera: Heleidae=Ceratopogonidae)

The alimentary tract of femaleCulicoides nubeculosusis simple. There is much similarity between it and that of other nematoceran and brachyceran bloodsucking flies. Among the interesting features observed are the following: 1. The mid-gut is composed of two portions, a tubular anterior segment and a dilated stomach, which show structural differences. 2. The peritrophic membrane, which is absent in the unfed female, forms around the ingested blood. Its substance is secreted by the epithelium of the stomach. 3. A simple rectal valve guards the opening of the small intestine into the rectum. 4. The Malpighian tubules are two in number, and they give attachment to muscular branches from different sources. 5. There are six accessory glands arranged in a rosette around the mouth of each salivary gland proper. Some of them may sometimes function as reservoirs for the secretion of the salivary glands proper. In one specimen, tumours at the base of the stomach and abnormal features in the Malpighian tubules were observed.