The summer creepy crawlies and how to repel them

Ah, the Scottish summers.. Beautiful scenery, unpredictable weather, blazing sunshine, gale force winds, torrential downpours and... midges, birch flies, deer flies, horse flies and ticks. Scotland is quite famous for its blood thirsty critters. Here's a short guide to where to find them, how to recognise them and how to protect yourself from becoming their dinner.

Midges

The Highland midge (Culicoides impunctatus) is a stuff of legends. A swarm of these beasties at sunset can obscure the skies and bring dread to the heart of the bravest camper. These tiny fling insects have an incredible ability to get into just about any orifice and have been known to bite an eyeball or two. They attracted to dark-coloured moving objects, particularly ones associated with carbon dioxide, they can also detect acetone and lactic acid. They like to nest in the acidic peaty soil and are prevalent in Scotland from late spring into the late summer (mid May to early September), which is why many say that early May and late September are the best times to visit the Highlands, especially if you plan to stay in the valleys. Midges are most active just before dawn and sunset but can bite at any time of day. Being rather small creatures, the midges are less active with wind speeds of over 6 mph and humidity below 60–75%. Based on this, the weather forecasts and the terrain, Smidge have developed a handy midge forecast that is active all summer and can be found here: https://www.smidgeup.com/midge-forecast/

Midge repellents

Luckily for us, midges do not carry any diseases that are dangerous to humans. However, their bites can be very painful and often weep for a few days and become inflamed. There are several ways in which you can protect yourself from the Highland midge. Covering your skin with thin fabric works really well, however, it may not be very comfortable on a hot summer day. Thin gloves and head nets help at camp and when hiking in sheltered valleys. Standard off the shelf insect repellents seem effective against the midges. These include the Jungle Formula (which contains DEET, which in high concentrations is toxic to the environment and may melt synthetic fabrics and plastic) and Smidge (which contains picaridin, synthesised to resemble the natural compound piperine, and designed to effectively block the antennal receptors of biting insects; picaridin is biodegradable and safe for the use with fabrics but can be toxic to fish at high concentrations). IR3535 (active ingredient in the BushWear No Tick wash in repellent, see below) is also effective at repelling midges. A long standing urban myth states that Avon Skin so soft is also a good option, however, rumours have it that it is not as effective since Avon changed their formula. Bog myrtle (Myrica gale) is commonly found on the Scottish wetlands and said to protect the wearer from Highland midge and fairies. To this day, bog myrtle is used in the production of soaps, creams and candles, however, the jury is still out on its effectiveness against the tiny Scottish vampire.

Ticks

Whilst the midges tend to emerge in late May and die down by September, the deer ticks (Ixodes scapularis) prefer wetter and colder weather, and hide in the bracken and heather on the Scottish hills. The adult ticks are active from March to mid-May and from mid-August to November. Don't be fooled into a false sense of security though, their offspring, which is the size of a poppy seed, called the nymphs feed from mid-May to mi-August. Ticks seem to like light clothing, CO2, heat and sweat. Recently, these blood thirsty arachnids (not insects) appear to be on the rise, partially due to a dip in deer cull during the COVID19 pandemic, and partially due to the recent changes in the grouse moor management favouring cutting the heather instead of the muirburn. Ticks have a complex life cycle, and unfortunately they can bite us in almost every stage of it. Tick nymphs can be very small and hard to see especially on a darker skin.

Tick removal

What makes ticks so dangerous is that ticks transmit Lyme disease which can have very unpleasant complications. Early Lyme disease symptoms include flu-like symptoms, pain, weakness, or numbness in arms and legs, changes in vision, heart palpitations and chest pain, a rash (that may nor may not be a bull's-eye rash), and a type of facial paralysis known as Bell's palsy. Not all ticks are infected, on average about 4% of ticks in England and Wales and 8% of ticks in Scotland carry the bacterium. Moreover, there is a very low chance of contracting Lyme disease from a tick bite if a tick is removed within 36 hours of attaching, and preferably within 24 hours. If you try to remove a tick, it is very important not to squeeze the tick's body and to remove the tick completely. Just pulling the tick off will result in the mouth piece remaining in the skin and a stressed tick will likely regurgitate the contents of the infected stomach back into the host. The correct way to remove a tick is to use special tweezers, tools or cards that are designed to be inserted close to the skin at the attachment point as seen on the picture below.

Tick repellents

The spray-on repellents that are effective against the midges, including the Jungle Formula (DEET) and Smidge (picaridin), are also effective against ticks. Other things you can try, especially if you are a keen wild camper, is soaking your clothes and tent in permethrin, or in R3535. Permethrin is a synthetic compound that is based on a substance extracted from chrysanthemum. Permethrin (which is available as a spray for fabrics and clothing) is biodegradable within 1-16 weeks and it has a low level of toxicity to birds and mammals, but it is highly toxic to insects, bees and fish. The use of Permethrin is restricted in the EU due to its potential harm to the aquatic life. IR3535 (ethyl butylacetyl-aminopropionate) is also biodegradable and not harmful to animals or the environment. The EU classed it as Class U, which means "unlikely to present acute hazard in normal use (WHO 2004)". Studies have shown that it directly activates bitter‐sensing gustatory receptor neurons in the insects, essentially making us appear less tasty. IR353 is available as a wash-in for clothes and fabrics, and as an active ingredient in on-skin insect repellents. In terms of natural remedies, a mix of citronella and thyme essential oils has been shown to be quite effective at repelling tick bites.

Birch flies

Another blood-sucking insect that Scotland likes to test us with are the birch flies also known as black flies or Simulium reptans. These are known as birch flies as they begin to appear as the birch trees begin to leaf and persist from May to September. Warm and wet weather is the early spring is ideal for these blood suckers and they swarm in shady areas near running water, usually in the morning. Adult males feed on nectar whilst the females feed on blood before laying eggs. Their bites can be quite irritating and they have been shown to transmit disease. They are prevalent in Speyside, however, they have also been reported farther North.

Birch fly repellents

Birch fly bites are shallow and they tend to go for areas of thinner skin, so wearing thicker clothing can offer some protection. Wearing light-coloured clothing seems to help as well. Although the standard insect repellents have been shown to be only partially effective, the IR3535, DEET and picaridin containing products repel them to a certain extent.

Horse flies

Horse flies or clegs (Tabanus sudeticus) do not travel in swarms which is just as well, as their bites can be extremely painful. They also prefer warm weather and are more often seen in continental Europe than in the wet Scottish climes. Having said that, with the climate warming up, they have been spotted in southern Scotland more and more (the Borders, Southern Uplands, Isle of Arran etc), and are most active from June to September. Horseflies are attracted to dark coloured objects and like to breed in wet soil close to bodies of water, and are mostly found in warm wet areas.

Horsefly repellents

Clegs bite and then fly away so swatting at them will not help you much. However, most of the commercially available repellents (DEET, picaridin, IR3535 and permethrin) are effective in repelling their bites.

Deer flies

Just when you thought you got the hang of it, mastered brushing, swatting and removing the biting critters off your skin, armed yourself with the insect repellents and correct clothing, nature invents another creature that is even more terrifying. Devil's spawn that looks like a hybrid between the midge and a tick, the deer flies or deer keds (Lipoptena cervi) are truly bizarre creatures. Deer flies emerge on the warm days in the autumn, usually in August and September. Both males and females feed on blood. They are very grippy and attach to their host really well (it makes them very difficult to just brush off your skin!), which is important as they usually feed for 15-20 minutes. When they do, they also shed their wings and burrow into the fur of their victims, so really they could be likened to a flying tick. The female incubates just one larvae in her body until it's ready to pupate and then gives birth to the prepupa which falls onto the forest floor, pupates and finds the next victim. The mum can then keep on producing these for up to 10 months! Deer fly bites can become inflamed and lead to dermatitis. Their gripping claws mean they are difficult to brush off so to remove them, you need to pinch them between your finger and thumb. As they mostly feed on the deer, there is also a risk of Lyme disease although the studies are still ongoing.

Deer fly repellents

Two studies found that keds are more attracted to dark-coloured rather than light-coloured clothing. They also mainly hunt by detecting warmth. Unfortunately the commonly used repellents such as DEET, IR3535 and picaridin do not work on deer flies. However, it has been shown that Permethrin causes ked's death within 20 minutes of biting and attaching, so soaking your clothes in it or using a permethrin-based repellent may help if you are travelling in an infested area.

So there you have it, an insect guide to the Scottish summer! Hopefully it hasn't completely put you off travelling North this year... It is important to note that whilst midges and ticks are quite common in Scotland, the rest of the creepy crawlies mentioned here are still relatively rare and either restricted to certain regions or needing warmer climes to truly swarm. The midge forecast is really handy and a tick forecast is currently being developed. It is very much possible to really enjoy summer in Scotland, climb the mountains and wild camp overnight, as long as you avoid wet and sheltered valleys, dress appropriately and bring an insect repellent.