Avoiding the bloodsucking bugs: What works to repel them and stop the itch

With the warm air comes a familiar whine in your ear and that inevitable itch on your ankle.

Before you curse the bloodsuckers away, Julia Kasper, lead curator of invertebrates at Te Papa, reminds us seeing these critters is a good thing for the ecosystem. Mosquito and sandfly larvae help filter waterways.

Nevertheless, it can seem like they have a personal vendetta against frequent targets – just ask Chloe Wright, co-founder of NZ Fun Camping Adventures.

"Jono [her husband] doesn't seem to get bitten as much. He's not immune, but they don't seem to love him as much, whereas they do quite like me if I go out."

Tourists also often arrive blissfully unaware of just how fierce New Zealand’s sandflies (aka black flies overseas) can be, she says.

According to Kasper, it's likely to be bed bugs, mosquitoes, and sandflies. Biting midges may pop up and are often mistaken for sandflies.

Bed bugs move in luggage or spread between rooms in places like hostels and apartments, she says.

While most of New Zealand's mosquito species prefer birds, it doesn't mean they won’t use you as a host if they need, she says. But they're not known to spread disease here.

Bed bugs are not picky, Kasper says. They hide in warm crevices — under mattresses, behind headboards, even in power sockets. Then they come out to feed at night.

If you spot tiny rusty or reddish stains on your sheets, that could be a telltale sign of their droppings.

Sandflies, meanwhile, breed in fast-moving streams, while mosquitoes prefer still water like plant saucers, buckets, or old tyres left outside, Kasper says. So, dispose or remove rubbish and kids toys in the garden after the rain.

"[They like] humid, like moist, damp, shady places to rest during the day and then at dawn or at dusk they come out, depending on the species again, when they are active and finding their hosts."

When camping, Wright recommends setting up somewhere dry and breezy.

Some species hang around low to the ground, so cover your legs, she says. If they’re really bad, a head net can be an option.

These clever insects use various cues, like chemicals, sebum, colour and temperature to detect their target.

"It's like mainly our breath that attracts them," Kasper says. "I mean, that's smart, right? Because they need a host, a living host, and we exhale carbon dioxide. So that's the main trigger for them."

For mosquitoes and sandflies, different wavelengths can also attract day-active and night-active ones.

Our skin, for example, emits a red wavelength – and they're drawn to those wearing red or dark and contrasting colours, she says.

If you feel you're a mosquito magnet, you may have some chemistry going on. Research has shown that mosquitoes do find particular chemicals that people emit attractive.

"But what we don't know is how to affect it, like in terms of dietary or hormones - we don't know how to change," Kasper says.

"We would know how to mask it with certain other chemicals that repels them. But we still don't know how we can change our body odour."

For serious bed bug infestations, Kasper says steam cleaning is key — not just vacuuming.

Wright says insect-repelling natural options include essential oils like lemon eucalyptus, witch hazel, tea tree, lavender, as well as balms derived from citronella grass.

"I don't like citronella candles. I don't really think they do much. It's probably fine if it's really still, but often there's quite a breeze."

Dermatology Society spokesperson AJ Seine says the best evidence is around pharmacy-grade repellents that contain DEET, which blocks some of the chemical cues that attract insects.

Their protection lasts about six to eight hours – longer than natural options which may only last about an hour or so, he says.

There's also permethrin, a fabric-grade insecticide you can treat clothes with.

If you're relying on electric zappers, Wright warns they're probably ineffective against sandflies because they're too small.

At night, she advises warmer, dimmer lights where you can enjoy the ambient lighting.

Campfire proves to be a good repellent because of the smoke, she says. (Just be wary of fire restrictions.)

Not all bites itch but the insect's saliva typically sets off an immune system chain reaction that releases histamine and causes the itch.

To soothe it, Seine suggests cold compresses which also slows the histamine release.

Calamine lotion, antihistamines, or even natural options like aloe vera, colloidal oatmeal, or a baking soda paste can bring relief, he says.

Wright's tip to work out if you need professional help is to draw around the bite with a pen. If the redness spreads, give Healthline a call.