Cattle-grub
Guides
Hypoderma
Warble Flies, Heel Flies, Bomb Flies, Gadflies
Hypoderma is a genus of large parasitic flies in the family Oestridae, commonly known as warble flies. Adults are non-feeding and live only to reproduce. Females deposit eggs on the legs and flanks of cattle and other ungulates; first-instar larvae penetrate the skin and migrate through the host's body, typically to the gullet or spinal canal, before settling in subcutaneous tissues of the back to develop. The larvae create characteristic swellings (warbles) visible on the host's hide. Two economically important species are H. bovis (ox warble fly) and H. lineatum (cattle warble fly), which cause significant damage to cattle hides and reduce animal welfare.
Hypoderma lineatum
Common Cattle Grub, Ox Warble Fly
Hypoderma lineatum is a parasitic warble fly in the family Oestridae, commonly known as the common cattle grub. Adults emerge from puparia in early May, approximately one month before the related H. bovis. Females oviposit on cattle during sunny, calm weather from late May through early September, showing a preference for open areas and avoiding water and shade. First-instar larvae penetrate the host's skin and migrate to the gullet, where they develop for an average of 42.5 days before moving to subcutaneous tissues of the back. The species causes significant economic damage to cattle through hide degradation, reduced milk yield, and irritation during adult oviposition activity. Unlike H. bovis, H. lineatum does not terrify cattle during oviposition; animals typically show little uneasiness.