How to Prevent Phorid Flies in Drains

Why Are Phorid Flies Called Humpbacked Flies?

Phorid flies are called humpbacked flies because of their highly distinctive body shape — the thorax is prominently arched.

Physical Features

• Viewed from the side, the back arches high like a hump.
• The head is tucked under the thorax, giving a head-down, back-high posture.
• Very small, 1–2 mm.
• Dark brown or black.

Origin of the Name

• "Humpbacked" — describes the arched thorax.
• "Fly" — they belong to the fly family.
• "Phorid" — from the scientific family name Phoridae; their behavior somewhat resembles fleas in that they can jump or scuttle quickly.

How to Observe?

• Use a magnifying glass or look closely up close.
• The side view is clearest — the distinctive humped profile is obvious.
• This is an important feature for distinguishing them from other tiny flies.

How They Differ from Fruit Flies in Appearance

• Phorid flies: Arched thorax, dark brown, eyes not prominent.
• Fruit flies: Rounder, flatter body, light tan, red eyes very noticeable.

Key Takeaway

If you see a tiny fly with a humpbacked profile from the side, it is almost certainly a phorid fly.