Culioides spp. are very small insects. They are usually seen flying in large swarms at dawn or dusk.
In the image below the size of a midge is compared with a mosquito and fly.
Due to their small size, they generally do not fly in windy conditions however they are easily spread by light winds.
Diagram to show the morphology of Culicoides spp.
Culicoides midges are about 1mm in length and have short legs. The wings contain stains and are folded over the back at rest.
Scanning electromicrograph of the biting mouthparts of a female Culicoides midge. Mouthparts are short and have borders and teeth.
Prof. Dr. H. Mehlhorn, Heinrich-Heine-Universitt Dsseldorf
The female midges require blood meals for egg production and have biting mouthparts. They are usually most active during the dusk, dawn and at night, preferring still, warm conditions for flying. Read more under Behaviour.