Midges are an ever-present drawback in fungi-rich woods . . .
Mention this diminutive insect, and most people think of the West Coast of Scotland. Indeed, the most aggressive of our 152 native species is often dubbed ‘the Highland Midge’. Unfortunately those of us who live in Wales know quite how false this soubriquet can be. While there are plenty of blood sucking insects to spoil a summer picnic, midges are undoubtedly the worst.
At just 1.4 mm, these may be small but they can make warm summer evenings a misery. To be fair, most midges prey on other insects, but the 50-strong Culicoides family rely on warm-blooded animals. In all 16 have been recorded dining on humans, but the worst offender is C. impunctatus.
Despite the nuisance factor, the underlying science is fascinating. Midges lay their eggs in permanently damp soil and as a result they are only a serious problem in areas which receive more than 50” of rain a year – which is why they are so at home along Britain’s West Coast. The larvae feed on tiny animals underground as they over-winter before emerging as adults the next spring.
Man’s difficulties are entirely down to the adult females. Males either go completely without food or drink plant sap but his mate needs richer fare. Her first batch of eggs use protein reserves she built up below ground, but to provide the yolk for subsequent eggs she requires blood. She is not choosy where this comes from: tests on gut contents reveal cattle, deer, sheep, cat, dog, rabbit and mice. As we all know to our cost, humans are not immune. All victims are bitten with short, blade-like, mouthparts. These make a shallow wound which oozes blood, stimulated by histamines in the saliva. After five minutes the midge is engorged and leaves.
The bite itself is painless, but the problems stem from the saliva which causes a mild allergic reaction. In most people this is no more than an itching sensation and mild swelling, but some react more violently. The person who claims midges target them is bitten no more frequently than their neighbour, merely more sensitised.
Repellents are only a partial solution. Most commercial brands are based on synthetic compounds which may be unsuitable for prolonged use. Extracts from several plant-based products can also be effective: for example citronella and herb oils such as thyme. Alternatively, local anglers swear by a 4:1 mix of baby oil and Dettol or (bizarrely) Avon’s Skin so Soft. Ultimately, however, nothing is entirely effective and the most practical solution is to avoid peak midge activity.