March Flies are found throughout Australia and consist of a number of different species. While they don’t travel in swarms like mosquitoes, they do make up for it with their painful bite. They are found in many differing environments and can be a real issue in Australia’s alpine regions.
These flies, specifically the females (because the males live on nectar) use their strong, piercing mouthparts like a needle to extract blood from animals (including people) to assist in the reproductive process.
March Flies have an exceptional work ethic. They will land on you, proceed to bite you and have the capacity to work their way through all but the thickest clothing fabric if you allow them enough time. The image in this article shows one attempting to bite me through my pants! I regularly see them trying to bite through leather boots, thankfully without any success. If there aren’t many food choices around they will follow you and keep on trying. The main saving grace is that they aren’t an issue in the colder parts of the day or in windy conditions. They usually start to come out as the day starts to warm up around mid morning and will persist until the temperatures start dropping again.
A couple of years ago I spent a day walking the Main Range Walk in Kosciuszko National Park in January and came across a group of non-hikers doing it in shorts, singlets and sandals. When I caught up with them at the end of the day and asked them how they went, they said they had learnt their lesson having to fight with the flies the entire day, getting constantly bitten.
These flies do not care about insect repellants and even 80% DEET will not deter them. I’m a bit of a rarity among hikers I see on trail as I almost exclusively wear long sleeved tops as well as long pants and the March Flies are just one reason for that.