The parasite whose larvae form warbles in subcutaneous tissue along the backs of cattle is which species?

The parasite whose larvae form warbles in subcutaneous tissue along the backs of cattle is which species?

• A. Gasterophilus species
• B. Hypoderma species
• C. Oestrus species
• D. Cuterebra species

Answer: (B)

The main concept here is identifying the parasite associated with warbles that form subcutaneous nodules along the backs of cattle. These warbles are produced by the larvae of warble flies belonging to the Hypoderma genus. In cattle, two species are classically involved: Hypoderma bovis and Hypoderma lineatum. Adult flies lay eggs on the cattle’s hair; after hatching, the larvae penetrate the skin and migrate through subcutaneous tissues, eventually forming the visible, pulsating nodules or “warbles” along the back as they mature. This pattern—subcutaneous nodules along the dorsum of cattle—is characteristic of Hypoderma infection, making it the correct association. The other options don’t fit this presentation. Gasterophilus species are horse bot flies whose larvae infest the horse’s stomach rather than cattle. Oestrus ovis is a nasal bot fly affecting sheep and goats, with larvae in the nasal passages. Cuterebra species cause cutaneous warbles in dogs, cats, and some wildlife, not specifically the cattle back lesion pattern described here. So, the parasite whose larvae form warbles in subcutaneous tissue along the backs of cattle is Hypoderma species.

The main concept here is identifying the parasite associated with warbles that form subcutaneous nodules along the backs of cattle. These warbles are produced by the larvae of warble flies belonging to the Hypoderma genus. In cattle, two species are classically involved: Hypoderma bovis and Hypoderma lineatum. Adult flies lay eggs on the cattle’s hair; after hatching, the larvae penetrate the skin and migrate through subcutaneous tissues, eventually forming the visible, pulsating nodules or “warbles” along the back as they mature. This pattern—subcutaneous nodules along the dorsum of cattle—is characteristic of Hypoderma infection, making it the correct association.

The other options don’t fit this presentation. Gasterophilus species are horse bot flies whose larvae infest the horse’s stomach rather than cattle. Oestrus ovis is a nasal bot fly affecting sheep and goats, with larvae in the nasal passages. Cuterebra species cause cutaneous warbles in dogs, cats, and some wildlife, not specifically the cattle back lesion pattern described here.

So, the parasite whose larvae form warbles in subcutaneous tissue along the backs of cattle is Hypoderma species.