Morellia simplex

Description

Around 9-10mm, a dark grey/black fly with a bold but short white stripe at the front of the thorax. The dark grey abdomen typically has a pale tip. The Morellia genus can be recognised by this generally dark colour, with vein m gently curving towards the wing margin and the middle tibia without a strong posteroventral seta, though posterodorsal and posterior setae usually well developed. Morellia simplex is probably the commonest of the genus and can be recognised by having a parallel-sided prosternum with lateral bristles.

Similar Species

Easily confused with Polietes domitor, but they are easily separated by the wing venation.

Identification difficulty
ID checklist (your specimen should have all of these features)
  • Vein m gently curving
  • Middle tibia without a strong posteroventral seta
  • Posterodorsal and posterior setae usually well developed
  • Overall appearance dark grey to black
  • Prosternum parallel sided and with lateral bristles
  • Grey dusting on the abdomen
  • Grey dusting on the thorax visible when viewed from behind
Habitat

It breeds in cattle dung so is usually found around cattle pasture.

When to see it

Peaks in April/May and in August/September.

Life History

It is sometimes referred to as a Sweat Fly and it can be a particular nuisance to cattle.

UK Status

Widespread and quite common in Britain.

VC55 Status

Fairly common in Leicestershire and Rutland

Leicestershire & Rutland Map

MAP KEY:

Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2025+ | 2020-2024 | pre-2020

UK Map

Species profile

Species group:
insect - true fly (Diptera)
Kingdom:
Animalia
Order:
Diptera
Family:
Muscidae
Records on NatureSpot:
15
First record:
24/05/2008 (Nicholls, David)
Last record:
21/06/2025 (Nicholls, David)

Total records by month

% of records within its species group

10km squares with records

The latest images and records displayed below include those awaiting verification checks so we cannot guarantee that every identification is correct. Once accepted, the record displays a green tick.

In the Latest Records section, click on the header to sort A-Z, and again to sort Z-A. Use the header boxes to filter the list.

Latest images

Latest records