Botflies are a common concern, especially regarding their presence in regions like California. This article clarifies questions about these insects, focusing on their biology, species found in California, and how to address potential infestation concerns.
Understanding Botflies
Botflies are a type of fly from the Oestridae family, known for their parasitic larval stage. Adult botflies do not feed; their primary purpose is reproduction. Female botflies lay eggs near or on a host animal. Once hatched, the larvae burrow into the host’s skin or sometimes enter through natural orifices.
This parasitic stage, where larvae develop within the host’s body, is called myiasis. Larvae create a breathing hole in the host’s skin as they grow. Different botfly species specialize in specific hosts, such as rodents, rabbits, or livestock. After maturing, larvae exit the host and pupate in the soil, eventually emerging as adult flies to continue their life cycle.
Botflies in California: Presence and Species
Botflies are present in California, though the most common species differ from those causing widespread human infestations in tropical regions. California’s botflies primarily belong to the Cuterebra genus, known as rodent or rabbit botflies. These Cuterebra species commonly parasitize wild animals like woodrats, mice, and rabbits.
Specific species like Cuterebra latifrons parasitize woodrats in California, with adult flies observed in areas like Marin County. Cuterebra lepivora is a California native that uses rabbits as hosts. While these botflies are widespread across North America, including the Pacific states, human cases are extremely rare and accidental. The human botfly, Dermatobia hominis, is native to Central and South America and is not endemic to California or the United States; any human cases in California are travel-related.
Addressing Infestation Concerns
Concerns about botfly infestations often arise when pets or livestock encounter these parasites. In California, domestic animals like dogs and cats can become accidental hosts to Cuterebra larvae, especially if they explore areas with wild rodents or rabbits. Signs of infestation in pets include a soft, swollen lump under the skin, often with a small, circular opening that serves as the larva’s breathing hole. This lump is typically found around the neck, head, or trunk.
If a botfly infestation is suspected in an animal, seeking veterinary attention is important. Veterinarians can safely remove the larva, preventing complications like infection or allergic reactions if the larva is damaged during removal. Prevention for pets involves limiting their access to areas with dense rodent or rabbit populations, particularly during late summer and early fall when adult botflies are most active. For humans, Cuterebra myiasis cases are rare and usually resolve with medical intervention, while human botfly (Dermatobia hominis) infestations are almost exclusively linked to travel to endemic tropical regions.