Homemade Bug Spray: What Really Works on UK Midges and Mosquitoes — and When to Buy the Real Thing

A still, damp evening in the Highlands, a cloud of tiny flies, and a sudden, urgent interest in insect repellent — that is the moment most people start looking into homemade bug spray. Mixing your own is genuinely appealing. You decide exactly what goes on your skin, you can skip DEET if you would rather, and a 100 ml bottle built from essential oils costs noticeably less than a shop-bought natural repellent.

What a homemade spray does not come with is a licence, a measured protection time, or any guarantee that the oils you chose will do much at all. A small handful of plant-derived actives have real published research behind them. Plenty of popular recipes smell lovely and deter almost nothing.

This guide is a research-based look at which ingredients are worth buying in the UK, how to mix them at a sane dilution, where DIY genuinely holds its own against the shop-bought competition, and the one situation where you should put the kitchen chemistry down and buy a licensed product instead. It draws on manufacturer specifications, published repellent research, expert publications and verified owner-review consensus — not on field trials run by anyone here.

Quick Picks

Prices move around, so treat all of the above as approximate at the time of writing.

The Recipe: Ratios, Base and Shelf Life

The single most common mistake in DIY repellent recipes is over-concentrating the essential oil. More oil does not mean more protection — it means more irritation and, with certain oils, more risk of a photosensitive reaction.

The standard ratio. Around 10–15 drops of essential oil per 100 ml of liquid, which works out at roughly 0.5–0.75% v/v concentration, is the sensible starting point for a blend you intend to put on your face and body. For clothing and feet you can go stronger — up to 30 drops per 100 ml, or approximately 1.5%.

The base. The workhorse mix is 10% witch hazel to 90% distilled water. Witch hazel acts as a mild emulsifier and gives the spray a little more grip on the skin than water alone, which is why it is in almost every recipe. For a stronger hold, particularly on ankles and wrists where midges and mosquitoes tend to land, you can switch to a 1:1 ratio of witch hazel to distilled water.

Storage. An unpreserved water-based spray has a shelf life of roughly 2–4 weeks. Mix small batches, label them with the date, and keep them in an amber glass bottle — amber glass blocks the ultraviolet light that degrades many plant oils and stops them losing potency in a sunny windowsill.

What it actually costs. This is where the folklore gets corrected. Tisserand lemon eucalyptus oil sells at roughly £9–£15 for a 9 ml bottle, which is about £1–£1.67 per millilitre. A 100 ml bottle mixed at a 2% dilution — the top end of what IFRA and Tisserand’s own dilution guidance allow for leave-on skin — needs around 2 ml of oil, so approximately £2–£3.34 in oil alone. Add witch hazel at roughly £1.25–£2 per 100 ml and the realistic floor for a 100 ml homemade spray is about £3.25–£5.50. A lighter body blend at 10–15 drops uses less oil and costs correspondingly less, but needs reapplying sooner.

That is still cheaper than the ready-made alternatives below — but it is pounds, not pennies. Anyone promising a DIY repellent at £1–£3 per 100 ml is either using a cheaper oil or mixing something far weaker than the label implies.

What the Research Actually Says

Lemon eucalyptus, citronellal and PMD — an important distinction

Lemon eucalyptus is the oil with the strongest evidence base, but the way it is usually described online is wrong.

Raw lemon eucalyptus essential oil is dominated by citronellal, not PMD. PMD (p-menthane-3,8-diol) is the compound produced when citronellal is refined and cyclised — it is a manufactured derivative, not something that comes out of the plant. That matters because the licensed repellents and the field studies behind them are built on refined PMD, not on the raw oil. Treat lemon eucalyptus essential oil as a botanical source of citronellal that can be refined into PMD — never as PMD itself. Citriodiol, made by Citrefine International, is the licensed, refined PMD product used in commercial repellents.

With that caveat in mind, the evidence for PMD is genuinely good. Fradin & Day’s 2002 field comparison published in the New England Journal of Medicine put PMD-based repellents in a similar bracket to low-concentration DEET. Carroll & Loye (2006) examined OLE/PMD protection duration, and Rodríguez et al. (2015) compared OLE/PMD against DEET directly. Protection windows are often cited in the region of about two hours, though that figure falls sharply against aggressive species and in humid, still conditions.

DEET and picaridin still lead

For all the appeal of botanicals, it is worth being straight about this: DEET and picaridin (also called icaridin) remain the most effective repellent actives, and both are considered safe when used according to the label — a position set out in NHS travel health guidance and echoed by the CDC. A homemade botanical spray is a legitimate choice for a garden barbecue or a low-pressure camping trip. It is not a like-for-like replacement for a licensed synthetic active in genuinely high-risk conditions.

Not all biting insects are the same insect

This is the point most DIY guides miss entirely. The Scottish biting midge, Culicoides impunctatus, is not a mosquito. It behaves differently, bites differently and responds differently. Aedes spp. mosquitoes, the daytime biters behind most nuisance bites, are different again, and Anopheles spp. — the malaria vector — is a third case entirely.

The PMD and picaridin evidence base is strongest against Aedes. The data for Culicoides is noticeably thinner. That is not a reason to ignore repellent in Scotland; it is a reason to be sceptical of any claim that a single blend handles everything.

The Avon Skin So Soft question

Few products have a stronger folk reputation in Scotland than Avon Skin So Soft, widely used on the west coast as a midge deterrent. The honest position is that the repellent evidence for it is weak, and its perceived effect is attributed partly to isopropyl myristate, a skin-conditioning ingredient that may form a physical barrier rather than a pharmacological deterrent. That is a community belief, not a demonstrated repellent mechanism, and the gap between the two is worth keeping in view when you read a confident forum recommendation.

How to Choose — and Stay on the Right Side of the Law

Dilution limits are not suggestions

IFRA and Tisserand dilution guidance puts the maximum for leave-on essential oils at typically 1–3%. A “10% lemon eucalyptus blend”, which circulates in some DIY recipes, is dangerously high for leave-on skin use and should not be mixed. The 0.5–0.75% body ratio above exists for a reason.

Phototoxicity

Lemon eucalyptus and citronella are both flagged for phototoxicity risk when used as leave-on skin products. In practical terms, that means not applying them immediately before extended sun exposure. If you are heading to a beach rather than a shaded campsite, this is the section to remember.

Children

PMD and OLE are not recommended for children under three, per NHS guidance. If you are treating a toddler, that rules out the lemon eucalyptus route entirely — and it rules out most homemade botanical blends built around it.

The GB Biocidal Products Regulation

Here is the genuine information gap in this category. In the UK, selling an insect repellent requires authorisation under the GB Biocidal Products Regulation, Product Type 19, with the Health and Safety Executive (HSE) as the competent authority. A homemade spray does not have that authorisation. It therefore cannot legally be sold, and it cannot carry a measured protection-time claim.

That is the honest trade-off, not a scare. A licensed product has been assessed for efficacy and can tell you how long it lasts. Your kitchen batch has not been, and cannot be. Which is exactly why reapplication frequency matters far more with a homemade spray than with a shop-bought one — you have no measured protection window to lean on, so you err on the side of topping up.

When to abandon DIY altogether

DIY sprays are not adequate for malaria-risk or tick-risk travel. For UK tick exposure, the relevant species is Ixodes ricinus, and for malaria you are into a completely different risk category. In either situation, use a licensed repellent as directed and follow travel health advice.

The DIY Ingredients

Tisserand Lemon Eucalyptus Essential Oil (9 ml)

Best for: the single best DIY active you can buy.

What you get: a 9 ml amber bottle of pure lemon eucalyptus essential oil, the botanical source of citronellal that the PMD evidence ultimately traces back to. At roughly 2 ml per 100 ml for a 2% blend, one 9 ml bottle makes several batches.

Standout strength: it is the only widely available essential oil in this category with a published field-research trail behind its refined derivative — Fradin & Day (2002), Carroll & Loye (2006) and Rodríguez et al. (2015) all sit downstream of this chemistry.

The honest caveat: raw lemon eucalyptus oil is not PMD, and it is not a licensed repellent. You are buying a starting material with a promising pedigree, not a finished product with a measured protection time.

Verdict: around £9–£15 for 9 ml is the right first purchase if you are building a homemade bug spray around one active.

Where to buy: typically stocked by aromatherapy suppliers, health-food shops and larger online natural-beauty retailers.

Naissance Citronella Essential Oil (100 ml)

Best for: classic citronella blends and anyone mixing in volume.

What you get: 100 ml of pure, steam-distilled citronella essential oil — a serious quantity compared with the 9 ml Tisserand bottle, and enough for batch after batch of spray.

Standout strength: value in bulk, and steam distillation means no carrier or dilution to account for when you do your own ratios.

The honest caveat: citronella is the weaker of the two botanicals here on the research front, and it carries the same phototoxicity flag for leave-on skin use as lemon eucalyptus. It is a blend component, not the headline active.

Verdict: around £9–£14 for 100 ml makes citronella the economical second oil in a blend rather than the one carrying the whole load.

Where to buy: typically found at natural-ingredients and aromatherapy retailers.

Boots Distilled Witch Hazel B.P.**

Best for: the base of almost every recipe in this guide.

What you get: a 200 ml bottle of distilled witch hazel at British Pharmacopoeia standard, which is the grade you want for skin application.

Standout strength: it is cheap, it is available UK-wide on the high street, and it behaves better than plain water. As a mild emulsifier it helps the oil disperse rather than sit in beads on the surface, and it gives the spray slightly more hold on skin.

The honest caveat: witch hazel is a carrier, not an active. On its own it repels nothing. It also will not preserve your batch — hence the 2–4 week shelf life.

Verdict: around £2.50–£4 for 200 ml makes this the cheapest and least glamorous part of the shopping list, and the one you will get through fastest.

Where to buy: Boots stores and boots.com.

The Ready-Made Alternatives

Smidge That Midge (75 ml)

Best for: Scottish midges, specifically.

What you get: a 75 ml spray built on 20% picaridin (icaridin), formulated in Scotland for Culicoides impunctatus — the Scottish biting midge, not a generic mosquito.

Standout strength: this is the rare product aimed at the insect people actually have a problem with on a west-coast camping trip. Picaridin is one of the two actives that public health bodies rank at the top of the effectiveness ladder, per NHS travel health guidance and the CDC.

The honest caveat: 75 ml is a small bottle for around £10–£15, so it is pricier per millilitre than a DIY batch — and it is a synthetic active, which is a deal-breaker if avoiding synthetics is the whole point of your DIY project.

Verdict: if your trip is Scotland in July or August, buy this alongside your homemade spray rather than instead of it.

Where to buy: Cotswold Outdoor and Go Outdoors.

Mosi-Guard Natural (100 ml)

Best for: a ready-made natural option that matches your DIY active.

What you get: the standard version is a 30% Citriodiol formulation; a 50% version exists for higher-risk zones. Both are the same active — Citriodiol, the licensed refined PMD from Citrefine International — and the two concentrations differ in duration, not in what is doing the work.

Standout strength: this is the commercial, licensed version of the chemistry your lemon eucalyptus oil is chasing. If you want to know what properly formulated PMD feels like before you commit to mixing your own, this is the benchmark.

The honest caveat: at around £9–£14 per 100 ml it costs more than a homemade batch at roughly £3.25–£5.50, and it does not carry the you-control-every-ingredient appeal.

Verdict: the natural repellent to buy when you want the PMD evidence base without the mixing, the dilution maths or the 2–4 week expiry clock.

Where to buy: Boots and Amazon UK.

Frequently Asked Questions

Does homemade bug spray actually work on Scottish midges? Partly, and less reliably than folklore suggests. The strongest published evidence for plant-derived actives such as PMD is against Aedes mosquitoes, while the data for Culicoides impunctatus — the Scottish midge — is thinner. A well-made botanical spray is a reasonable low-stakes deterrent on a still Highland evening, but it is not a like-for-like substitute for a licensed product formulated specifically for that species.

Is lemon eucalyptus oil the same thing as PMD? No, and this is the most common error in DIY recipes. Raw lemon eucalyptus oil is dominated by citronellal. PMD is produced by refining and cyclising that citronellal, and it is the refined compound — sold as Citriodiol — that the field studies and licensed repellents are based on. Treat the oil as a botanical source, not as a finished active.

How often should I reapply a homemade spray? More often than a shop-bought one, because your batch carries no measured protection time and no HSE-authorised efficacy claim. Published protection windows for PMD-based repellents are often cited at around two hours, and that figure drops in humid, still conditions. Reapply on that sort of timescale, and sooner on ankles, wrists and the back of the neck.

Can I legally sell homemade bug spray in the UK? No. Selling an insect repellent in the UK requires authorisation under the GB Biocidal Products Regulation, Product Type 19, with the HSE as the competent authority. A homemade spray has no such authorisation, so it cannot legally be sold, and it cannot carry a protection-time claim even as a gift with a description attached.

Is a DIY repellent safe for young children? PMD and OLE are not recommended for children under three, per NHS guidance. Since lemon eucalyptus is the best-evidenced DIY active, that effectively rules out the strongest homemade option for toddlers. Dilution matters too — leave-on essential oils should typically sit at 1–3% maximum for adults, and lower is better for children.

What dilution should I actually mix? Around 10–15 drops of essential oil per 100 ml, or roughly 0.5–0.75% v/v, for face and body use. You can go up to about 30 drops per 100 ml (approximately 1.5%) for clothing and feet. Some recipes circulating online call for a 10% lemon eucalyptus blend — that is far above the IFRA and Tisserand leave-on maximum and should not be mixed.

Why does my batch go off so quickly? Because it is an unpreserved water-based product. Expect roughly 2–4 weeks of useful life, less if it sits somewhere warm. Mix small batches, date the bottle, store it in amber glass to protect the oils from ultraviolet light, and throw out anything that has changed smell or colour.

The Bottom Line

A homemade bug spray built around lemon eucalyptus, mixed at 0.5–0.75% for body use over a witch hazel and distilled water base, is a sensible, low-cost option for gardens, campsites and low-risk evenings — realistically £3.25–£5.50 per 100 ml against around £9–£14 for a comparable volume of Mosi-Guard Natural or £10–£15 for 75 ml of Smidge. What it will never be is a licensed product: no measured protection time, no authorised efficacy claim, and no legal route to sale under the GB BPR PT19 regime.

For Scottish midges in peak season — July and August, within the May–September window that NatureScot’s seasonal data describes — a picaridin formulation such as Smidge is the pragmatic pairing. And for malaria-risk or tick-risk travel, including UK exposure to Ixodes ricinus, leave the kitchen chemistry at home and use a licensed repellent as directed.