Gasterophilus pecorum

G. pecorum has four main life stages: egg, larvae, pupae, and adult.[11] Unlike the other species of Gasterophilus, who usually lay their eggs on the hair of the equids, adult G. pecorum lay eggs on blades of grass like the Stipa caucasica, near water and the paths used by the equids.[12][13][14] Once the egg is consumed by the host, a larva emerges and makes its way into equid's digestive tract where it will remain for 9–10 months to mature, and in the process will go through three larval instars. After the larva is finished developing, it then is released from the host via the host's feces. Here the larva pupate and turn into adults. Adults only live for about 1-4 days since they cannot eat, but they are capable of producing large amounts of eggs.[11][15] This alongside G. pecorum oviposition strategies have allowed them to become responsible for a majority of the botfly infections in KNR.[12]

An infection of G. pecorum is a major problem for an equid. The larval instars of G. pecorum can cause their host to develop gastrointestinal myiasis, and these infections have also been shown to affect the microbiomes of the host.[16] Equids may take oral medications, avermectins for example, to help reduce botfly infections. It is recommended that the equids be treated once in the early summer and once again in the fall to help minimize the later larval instars.[17]