What is the common name for the fly that can cause priapism?

The common name for the fly that can cause priapism is the Spanish fly. This is because Spanish fly, which is derived from the crushed bodies of the blister beetle (Lytta vesicatoria), contains a compound called cantharidin, known for its irritating properties and ability to cause inflammation. Cantharidin can stimulate blood flow and has historically been associated with inducing priapism, a prolonged and often painful erection.

Unlike other options, such as the house fly, horse fly, and flesh fly, these insects do not have the same pharmacological properties or historical context linked to the condition of priapism. House flies are common pests but do not have any medicinal or adverse effects related to sexual arousal. Horse flies are known for their painful bites but do not produce compounds that cause priapism. Flesh flies are associated with decomposition and carrion, having no connection with this particular condition. Thus, the Spanish fly stands out as the one specifically recognized for its association with priapism due to its unique chemical composition.