Exorista mella

On average, the larval development of E. mella lasts for 10 days.[5] Larvae emerge from their eggs on the surface of their hosts, after which they burrow into the host for the remainder of their development.[2] Delays in development occur when the host molts.[4] If the host does not molt, larvae are able to develop within an average of 6.4 days, as opposed to an average of 12.9 days if the host does molt.[6]

E. mella larvae are able to emerge from any stage (i.e. prepupae and pupae) of their host during their development.[2]

The lifespan of adult E. mella flies varies. Males typically have an average lifespan of about 29.5 days, while females survive an average of about 38.0 to 40.6 days.[4]

The earliest recorded viable eggs in a study were from females 48 to 72 hours old, which had immediately mated after emerging.[7] Even without having mated, newly emerged females have also been documented to be able to oviposit infertile and consequently unviable eggs. The gestation period lasts for an average of at least 2 days upon emergence from the host.[4]

Female E. mella flies extend their ovipositor onto the surface of their host of choice to lay their hard-shelled eggs.[1] On average, a female E. mella fly can oviposit about 150 eggs during her lifespan.[8] The most an E. mella fly has been recorded to oviposit on a single host for one study was 65 eggs.[7] Typically, the oviposition period lasts for about 24.8 days. E. mella typically oviposit on the cuticle of their host, but have also been documented to oviposit on the head capsule, setae, prolegs, and on the abdomen of hosts.[4] Though they prefer to oviposit on live hosts, females were also observed to oviposit on the surface of dead hosts. Larger females were also observed to oviposit a greater number of eggs than smaller females.[8]

As a polyphagous and generalist fly, E. mella feeds on a variety of hosts. It has been recorded to parasitize the following families of caterpillars: Arctiidae, Noctuidae, Notodontidae, Lymantriidae, and Lasiocampidae.[2] E. mella has also been noted by one study to be one of the core three parasitoids to account for the mortality of a variety of caterpillars.[9] Some of these hosts, such as the Grammia geneura moth, have been observed to be able to fight back against parasitism by E. mella through a particular diet of plants, as well as surviving through adulthood.[5]

Female E. mella flies spend time browsing hosts by moving around habitats where they are likely to find hosts, such as in low shrubs and herbs that their hosts feed on.[8] When choosing a host, the flies usually drum their feet on its body to determine if it is an adequate and living host.[1] One experiment found that E. mella flies respond more strongly to certain characteristics of a host than others, one such characteristic being the movement of the host. The more the host moved, the faster the flies were observed to approach the host.[8] Female E. mella flies have been found to preferentially oviposit on larger hosts.[2] They have also been found to prefer host caterpillars that are in their late instar stage of development.[5]

One experiment observed more experienced flies learning and behaving in a different way than inexperienced flies. Where more experienced flies typically oviposited more eggs onto a host, experienced females were also documented to be able to recognize suitable hosts faster than inexperienced hosts and tended to oviposit on live hosts more often.[8]

Another experiment looked into the potential of E. mella flies as biocontrol agents in agriculture for certain pests. Where parasitism of the host rarely lets the pest that is chosen as a host live. The study itself looked at the ability of flies to do so either by depositing their eggs into a host described as macro egg laying or on the plant which they feed off of described as micro egg laying. E. mella was one of a couple of flies in the study that could deposit on both the plant and the host, with parasitism having a greater percentage to occur within a host.[10]