Physocephala tibialis is a species of thick-headed fly (family Conopidae) found throughout the eastern United States, often near flowering plants. The adult fly is primarily black with a yellow face and thin white stripes on the abdomen. It is commonly found along the east coast of the United States and is often found near flowering plants.

P. tibialis flies parasitize many different species of bees by laying their eggs inside the abdomen of their host. The larva hatches inside of the host and grows and develops until it takes up the majority of the host's abdomen. The host then dies and the larva envelopes itself in a puparium and pupates inside of the corpse. After an extended period of pupation, the adult emerges from the corpse of the host bee. When a bee becomes parasitized by a P. tibialis larva, certain behaviors such as induced grave digging and changes in flower preference often occur.

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