Size matters to the Scottish biting midge

Electron micrograph of a Highland biting midge
Photo: © Trees for Life

Walking in Scotland during the summer months can be blighted by midge bites. But have you wondered why this is a significant problem for some and not for others?

Well it seems that the Scottish biting midge show a definite preference for tall men and overweight women. And further more it's possible to inherit a tendency to be bitten from your parents.

These are the findings of a questionnaire-based study published recently in BMC Public Health by researchers from the University of Aberdeen and Rothamsted Research which is an institute of the Biotechnology and Biological Sciences Research Council (BBSRC).

Data for the study was collected in 2008 at a duathlon event held annually round the shores of Loch Ness, the First Monster Challenge.

Analysis of the data showed that the Scottish biting midge is more likely to bite taller men and larger women.

Commenting on the findings, Dr James Logan from BBSRC who ran the study with Professor Jenny Mordue from the University of Aberdeen said,

"The preference for taller people could be associated with midge behaviour and flight patterns, as midges are found at great numbers with increasing height, particularly between 1-4 metres."

"Larger people would provide a more substantial visual target for host-seeking midges as well as greater amounts of heat, moisture and attractant semiochemicals (behaviour modifying chemicals), such as carbon dioxide, which are the cues the insects use to locate a suitable blood meal."

The researchers also confirmed previous findings which suggest that about 15% of us are rarely bitten at all and that this 'unattractiveness' to the midge seems to run in families.

"The reason some people are bitten less by mosquitoes and midges is due to the production of repellent chemicals in their body odour. It is possible that the biosynthesis or release of these natural repellents is under genetic control and could be inherited," said Dr Logan.

In Scotland there are just under 40(!) different species of midge but it's 'Culicoides impunctatus' which is most likely to have bitten you. This little creature is thought to be responsible for possibly 90% of all bites on humans. It's found throughout Scotland but is most prevalent in the west and north. You're unlikely to come across any midges about 500 metres - the wind reduces their ability to fly.

I'm heading for the hills!

For more information: To bite or not to bite! A questionnaire-based survey assessing why some people are bitten more than others by midges by James G Logan, James I Cook, Nina M Stanczyk, Emma NI Weeks, Sue J Welham and A Jennifer Mordue (Luntz).
BMC Public Health 2010 110:275

“We were camping a few years ago at a campsite next to Loch Lomond. Three of us had just a few bites but my husband made the silly mistake of leaving the tent in shorts and tee shirt. Within seconds he was covered and spent the remainder of the week in agony - and he is only 5 foot 4 inches.”

Anne Jackson, Harrogate

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