The mouth parts and digestive tract of adult dung beetles (Coleoptera: Scarabaeidae), with reference to the ingestion of helminth eggs

1. The chewing mouth parts of adult dung beetles are specialized for efficient ingestion and mastication of soft feces. The terminal lobes of the maxillae are spatulate and hairy, the hypopharynx large and mobile. The complex mandible has a flexible, fringed, blade-like incisor lobe and a large molar lobe which bears a smooth, resilient grinding area. This consists of a multitude of precisely arranged triturating structures of a minute size that is directly correlated with the size of the beetle. The asymmetrical molar lobes are closely apposed. 2. The tubular digestive tract consists of a short pharynx and esophagus, a very long, coiled ventriculus lined with a peritrophic membrane, four Malpighian tubules, and a short hind gut. Proventriculus, dilated storage chambers, and salivary glands are absent. 3. Alimentation, nutrition, comparative morphology, and the relation of dung beetles to parasitic heminths are reviewed and appraised. The grinding efficiency of the mandibles, varying with species, may be a significant factor in the susceptibility of beetles to infection by ingested parasites.