What term describes the feeding habits of the female horse and deer fly?

The term that accurately describes the feeding habits of the female horse and deer fly is "parasitic." Female horse and deer flies are known for their blood-feeding behavior, which they utilize to obtain nutrients necessary for egg development. This behavior classifies them as ectoparasites, as they rely on a host organism for sustenance without typically causing death.

Parasitism implies a relationship where one organism benefits at the expense of another, which is precisely what occurs during the feeding process of these flies. The flies pierce the skin of their hosts, often large mammals, to access blood, thereby obtaining the essential proteins and iron for their reproductive cycle.

In contrast, the other choices reflect different feeding behaviors. "Herbivorous" refers to organisms that primarily consume plant material, "detritivorous" describes those that feed on decomposing organic matter, and "omnivorous" denotes organisms that eat both plant and animal matter. These classifications do not apply to the feeding habits of horse and deer flies. Thus, understanding parasitism allows for a clear identification of the feeding behaviors exhibited by these specific flies.