Bug FAQHairy Kelp Fly
Chaetocoelopa littoralis · Order: Diptera · Family: Coelopidae
The hairy kelp fly is a small, about 7 mm long, grey fly with reddish-brown antennae and long black hairs on its legs and abdomen. It lives on decaying seaweed and kelp washed up on New Zealand beaches, where it can appear in large groups.
Source: Wikipedia
How to recognize it
It has a broad grey band on the head near the ocelli, reddish-brown antennae, palps, proboscis and legs, and clear wings with brown veins.
Source: Wikipedia
Size
Adults are about 7 mm long and have long, hairy legs.
Source: Wikipedia
Where it lives
They are found in piles of decaying seaweed and kelp on the shore and may gather in large numbers.
Source: Wikipedia
What it eats
Larvae feed on rotting algae and the microorganisms that live on it.
Source: Wikipedia
Life cycle
Larvae pass through three instar stages before pupating in sand higher up the beach. Males that are larger have higher mating success because they can overcome female resistance.
Source: Wikipedia
Where it comes from
The species is native to New Zealand.
Source: Wikipedia
More photos
Questions people ask
What do the larvae eat?
The larvae consume decaying seaweed and the microorganisms associated with it.
Source: Wikipedia
Where can I find hairy kelp flies?
They live on washed-up seaweed and kelp on New Zealand beaches, often in large groups.
Source: Wikipedia
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Chaetocoelopa_littoralis
Look it up elsewhere: GBIF · iNaturalist · BugGuide · Wikipedia
Text written 2026-10-23 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-23.