Biting Midges, "No-See-Ums" & Sweet Itch In Horses

Biting midge identification

Biting midges are tiny (0.6-1.5 mm) flies in the family Ceratopogonidae (see photo right). These flies are variously called biting midges, gnats, "sand flies", no-see-ums, and punkies*. The midges are nearly invisible to the unaided eye and can pass through normal window screens and even some mosquito netting. When under attack by these flies outdoors people often say something like "I'm getting bit but I can't see what's biting me!". While there are many non-biting midges, or gnats, these are the only midges that bite. At rest biting midges fold their wings across the back like scissors. The wings may be spotted and somewhat hairy.
 

Biting midges develop in damp, organic soils

Biting midges develop in wet, marshy, or swampy soil but even a small spring can produce large numbers of these flies. The larvae are aquatic or semi-aquatic and midge infestations tend to be located near poorly drained or constantly wet soil.

Infestations can be very "spotty" across fields, high in some wet areas while absent from drier spots. Biting midges are poor fliers so are not able to move far from their breeding habitat. Short of draining the wet ground it is nearly impossible to eliminate midges. Instead it is best to use repellents to protect both people and horses from bites (see below).