Common Lagoon Fly

Eristalinus aeneus · Order: Diptera · Family: Syrphidae

Also called: Large Spotty-eyed Drone Fly, Syrphid Fly

No source yet on danger. We have no source yet on whether it bites, stings or damages anything.
Common Lagoon Fly
Photo: Michael Knapp, CC BY

It can be recognized by spotted eyes, shiny second and third abdominal segments, faint grey stripes on the thorax, and distinctive leg markings (-). It lives around freshwater habitats such as lagoons, ponds, slow rivers and irrigation ditches, and is found worldwide (-).

Source: Wikipedia

How to recognize it

Eyes have obvious black spots. Abdominal segments 2 and 3 are completely shiny. Thorax dorsum shows faint greyish stripes. Males have eyes that meet on the frons; females have bare lower eye halves (-). Hind tibiae have a black ring past the middle and tarsi segments 2-4 are darkened.

Source: Wikipedia

Size

Wing length ranges from 6.5 to 9.25 mm.

Source: Wikipedia

Where it lives

In northern areas larvae live in seapages and brackish rock pools, elsewhere they use various freshwater habitats.

Source: Wikipedia

What it eats

Larvae develop in rock pools with decaying seaweed.

Source: Wikipedia

Life cycle

Adults are active from April to October and overwinter as adults. Larvae occupy freshwater seapages, brackish pools, animal dung and sewage farms depending on region.

Source: Wikipedia

When you see it

Flight period spans April through October.

Source: Wikipedia

Where it comes from

The species has a cosmopolitan distribution.

Source: Wikipedia

Where it is found in the US

Recorded in 45 of 51 states and DC. Most records: California, Maine, Texas, Washington, Massachusetts, Nebraska, New York, New Hampshire.

Darker = more records. Counts are museum and citizen-science records, not population size.

Source: GBIF

Status: introduced in Canada. Source: iNaturalist

Months it is reported in the US

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Source: GBIF

More photos

Common Lagoon Fly photo 3
Photo: Therese Phillips, CC BY
Common Lagoon Fly photo 4
Photo: Even Dankowicz, CC BY
Common Lagoon Fly photo 5
Photo: Wendy Jegla, CC BY
Common Lagoon Fly photo 6
Photo: unknown, CC0

Same family (Syrphidae)

Common Drone FlyCommon Drone FlyEristalis tenaxHarmlessMarmalade Hover FlyMarmalade Hover FlyEpisyrphus balteatusMargined CalligrapherMargined CalligrapherToxomerus marginatusEastern CalligrapherEastern CalligrapherToxomerus geminatusYellow-haired Sun FlyYellow-haired Sun FlyMyathropa floreaThick-legged Hover FlyThick-legged Hover FlySyritta pipiens

Sources

  • Wikipedia: https://en.wikipedia.org/wiki/Eristalinus_aeneus

Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia

Text written 2026-10-22 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.

How this page works

This is one bug's fact sheet. The colored box at the top says whether it is dangerous. Sections below cover how to recognize it, whether it is a pest, and how to deal with it. The US map shows which states have records; tap a state to see other bugs there.

Every fact on Bug FAQ comes from a named source (university extension sites, government agencies, GBIF, iNaturalist, Wikipedia). The source is linked next to each section. If we have no source for something, we leave it out.