How does the Human Bot Fly achieve its 'dirty' status regarding personal intrusion?

Answer

By laying eggs under the skin of mammals, developing larvae cause painful, seeping pustules.

The Human Bot Fly is considered invasive and dirty because it skips surface filth entirely and becomes a subcutaneous parasite, causing painful pustules as the larvae develop.

How does the Human Bot Fly achieve its 'dirty' status regarding personal intrusion?
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