Hitchhiking bot fly babies

Bot fly larvae – note the black spines they use to anchor into host tissue!

You may have heard of the cute and fuzzy botfly, whose larvae take up temporary residence inside mammals while they develop and eat living tissue (called myiasis). In humans, these larvae typically develop underneath the skin, forming a lump that seeps pus and can be painful (just google ‘botfly wound‘ for a fun treat for your eyes). Rarely, they have been known to infest the brain, causing convulsions and bleeding. In wild and domestic animals, botflies tend to migrate to various tissues, and can cause respiratory complications, organ malfunction, and death. Economic losses of livestock have been huge in the past.

Gross photos of wounds or videos of larvae removal are always fun, but what’s interesting (especially to a mosquitologist like me) is that adult female botflies have other insects perform work for them. Laying eggs themselves on a host can put the female botfly in danger of being killed, so a female grabs an unsuspecting mosquito, and glues her eggs on the underside of the mosquito’s body (where it can’t be groomed off). When the deed is done, the botfly releases the mosquito back to business as usual, along with newly acquired hitch-hiking babies.

Botfly eggs hitching a ride on a mosquito

After a number of days, the mosquito feeds on a host again for blood. The botfly eggs take a cue from the host’s body temperature, hatch and burrow into the host (look at their teeth!). While developing, the larvae breathe through a little opening in the skin, eating tissue and growing. After about 4-18 weeks, the larvae eventually emerge, drops in the soil to pupate and become adults, starting the life cycle over again.

My lingering questions: What effect do these eggs have on mosquito flight? Why do the botfly adults seem to prefer to lay eggs on mosquitoes and not other biting flies?