Cuterebra fontinella grisea

Adults of Cuterebra fontinella grisea have not been described separately from the nominate subspecies at the level of detail available in the provided sources. The species C. fontinella as a whole is distinguished from other Cuterebra species by host association with mice rather than rabbits or squirrels. Rabbit-infesting Cuterebra species typically exhibit red bands in the eyes, which are not present in mouse-parasitizing species. Larvae form large subcutaneous warbles with a breathing pore at the skin surface.

Eggs are deposited in the host's habitat near burrow entrances of small mammals. The subspecies occurs in temperate deciduous forest regions where white-footed mice are abundant. Adults, when encountered, are found in open areas including glades and forest edges.

The subspecies has been documented in Missouri based on parasitism of white-footed mice in field studies at Truman State University. The broader species C. fontinella occurs in eastern North America.

Larvae spend approximately one month in the host. Adults emerge from puparia in spring (observations include April and May in Missouri). Bot flies overwinter as pupae in the soil.

• Peromyscus leucopus - primary hostWhite-footed mouse; larvae develop subcutaneously forming warbles

Females oviposit in host habitat where eggs await passage of a host. Host body heat stimulates egg hatching. First instar larvae enter through natural orifices or wounds, migrate to subcutaneous locations, and form warbles. The larva molts to second instar within the warble and feeds on host fluids (not tissue). After roughly one month, the third instar larva exits the host, burrows into soil, and pupates. Adults emerge from puparia, do not feed, and live only briefly to reproduce.

Adults are rarely encountered in the field, suggesting cryptic or low-activity behavior. The subspecies shows strong host specificity to white-footed mice, attributed to long shared evolutionary history.

As a specialist parasite, C. fontinella grisea represents a case of relatively benign parasitism where infected hosts may experience extended longevity compared to uninfected individuals. This counterintuitive outcome has been attributed to co-evolutionary adaptation reducing virulence in long-term host-parasite associations.

No direct human parasitism is known for this subspecies. The related tropical species Dermatobia hominis parasitizes humans, but C. fontinella grisea is restricted to temperate regions and small mammal hosts. The subspecies has been studied for its effects on wild mouse populations.

• Cuterebra abdominalisParasitizes rabbits rather than mice; adults resemble bumble bees with distinctive coloration
• Cuterebra buccataRabbit bot fly with red eye bands in adults; distinct host association
• Cuterebra emasculatorParasitizes tree squirrels and chipmunks; warbles often located near genitalia (though name is a misnomer)

• parasitoid
• endoparasite
• mammal parasite
• myiasis
• rodent parasite
• bot fly

• BugGuide
• iNaturalist taxon
• Diptera | Beetles In The Bush | Page 6
• Oestridae | Beetles In The Bush
• Newly emerged rabbit bot fly | Beetles In The Bush