The Blandford Fly

Black fly sucking blood

This black fly gets its name from the area where it once plagued and sent hundreds of people to visit their doctors. It’s not like the fly exists only in Blandford. During the summer of 2014, a lot of locals had raised their voices against the cuts in funding, specifically towards controlling the population of the Blandford fly in the River Stour. This gave the story a lot of media coverage. What was this small black insect, that could make 2.5 thousand people sign a petition to continue treating the River Stour?

What exactly is the Blandford Fly?

The Blandford fly is a type of black fly in the UK, mostly seen in populated areas alongside rivers. It has been spotted in the Blandford area ever since 1960, and in the spring of 1972 hundreds of people needed medical assistance, thanks to the painful bite of the fly. Simulium posticatum is the Latin name of this black fly. The locals share different legends about how this species came to the area, but the truth is that Simulium posticatum was always present near the rivers of southeast England. The Blandford fly common name stuck, at least in the UK, and this is how the species is mostly known in the country. However, in recent years it spread far beyond Blandford, you can check where the Blandford fly has been spotted in the UK.

Blandford flies are 2-3mm long, bloodsucking black flies with round abdomens, tiny heads and short antennas. They have yellow-ish stripes on their abdomens, which could be used to tell them apart from other insects. The one thing that sets them apart from other tiny black flying insects is their bite!

Is your property infested with flies?

Get assistance from a local fly exterminator!

Call us

The life cycle of the UK Blandford fly

The blackfly has four stages of its life cycle. Egg, larva, pupa and adult fly. In the egg stage, it is attached to low hanging grass leaves near water bodies, rocks or other objects that are partly submerged in water. This is the incubation stage. After the egg hatches, it enters its larva stage. The larva feeds on bacteria, algae or tiny aquatic animals, which it filters out from the water. You can notice the larva in shallow water with its body orientated towards the stream. After the larva grows enough it will weave its cocoon and enter the pupa stage. The pupa also spends its life in the water. In this stage, another metamorphosis takes place and the adult fly flies out in search of a mating spouse. This entire cycle can take as little as a few weeks during the warm summer months. The time for the development of blackflies depends on the temperature of the water and currents, mostly.

Blandford fly bite

Similar to female mosquitoes, female Blandford flies need a blood meal to mature their eggs. This is why during the summer, when it’s their breeding period, you could experience the painful bite of a Blanford fly around areas of water. They are most active between May and June. Apparently, black fly bites are some of the most common bites, seen on people in the UK.

The typical spots for their bites are on the lower limbs because these black flies tend to fly close to the ground. Bites on the arms are not something extraordinary but are rare. The bite from the Blandford fly is described to cause a painful stabbing sensation. It often results in blisters and sometimes, blue to purple lesions are formed around the bitten spot.

Depending on your sensitivity to the saliva of the Blandford fly, you can experience different local irritations like redness, itchiness, pain, joint pain and even high temperature. Most people develop skin irritations that could be treated with over-the-counter medications (antihistamines and analgesics, however, on rare occasions - even antibiotics if the bitten spot is scratched and infected). Those irritations last for a few days but are painful to most who have been bitten.

How to avoid Blandford fly bites

Wear clothes that completely cover your legs, down to the ankles. Combine them with high socks and apply insect repellents with DEET when near rivers, streams and similar. If you notice a swarm of low-flying flies, best avoid passing near it.

How to treat Blandford fly bites

If you suspect you have been bitten by a black fly, you should take action. Your skin is irritated, you have felt a strong piercing pain and probably notice a blister forming by the time you get home. Here is what you should do.

  • Make sure you clean the spot with warm water and soap and be careful not to pop the blister.
  • If the bitten area is swelling, apply a cold compress.
  • Make sure you are not rubbing the area to avoid spreading the fly’s saliva.
  • If your ankles are swelling, elevate your legs on a pillow and rest more.
  • Take oral antihistamines. Avoid creams, as they can cause additional irritation.
  • Local anaesthetics can be used to reduce inflammation. Opt for sprays, not creams as you don’t want to rub them in.

Having trouble with flies buzzing arround?

Important (Note)
If your symptoms are persistent and you have them for more than three days, seek a medical opinion. If you have any troubles breathing or swelling of the face or tongue, seek immediate medical assistance.

And if you have troubles at home with other less pernicious but still annoying and disease-spreading flies, don’t hesitate to book a professional fly pest control service with us!


We only aim to provide some useful facts about flies. Anyway, we don't provide any medical advice.

Read more

Generic selectors
Exact matches only
Search in title
Search in content
Post Type Selectors
Search in posts
Search in pages
Search in posts
Search in pages
Search in posts
Search in pages