RUUD KLEINPASTE

- A guide to bugs that bite.

Instead of starting this story with one of those routine warnings that some content may be upsetting to readers and how discretion is advised, I’d like to take the positive approach by telling you something you already know: We live on a biological planet that is run by a fabulous web of biodiversity. Everything is connected – plants, fungi, birds, mammals, invertebrates, bacteria, pathogens, predators, pollinators and parasites.

Seeing we belong to the Mammalia (and the gardening sub-species of Homo sapiens) we are just as much connected to that incredible connective system we appreciate so much – until, of course, the mosquitoes arrive at the barbecue. Even the anti-vaxers will declare war on these very clever consumers of human blood, and not just because the female mozzies are very skilled phlebotomists.

Most of us will know the background story to the mosquito nuisance. The females require good protein to develop eggs and the ecological association with humans is the perfect match. We exhale carbon dioxide (CO2) which the insects can detect from quite a distance. They fly up the plume of this gas, get closer to the target, smell attractive human odours and even feel subtle differences in temperature to further select a nice, wide blood vessel close to the surface of the skin. The proboscis with a number of stylets literally saws through your skin and into this blood vessel to mine that valuable protein. As they are feeding, they inject some saliva with anticoagulants so that the blood doesn’t clot, which would spoil the whole experience for the mosquito.

For us hosts, this saliva cocktail triggers an immune response with histamines which make the bite region rather itchy for a few days.

As I am the “mozzie magnet” of the family, I can vouch for the fact that scratching will only make matters worse and that a good repellent is worth its extraordinary price in chemist shops.

I do realise, however, that I’m never going to win you lot over to actually appreciate mosquitoes for the jobs they do.

As we all know, mosquitoes breed in stagnant water, where the larvae actually do a brilliant job in consuming the organic matter and bacterial soup; yes, they clean the water! (While we are on the topic of ecosystem services, male mosquitoes don’t bite at all: they are quite competent pollinators of the flowers you’d like to see in your garden.)

Removing any objects that can hold water for prolonged periods of time is the number one action to take around the garden. Buckets, saucers under plant pots, blocked guttering, waterlily containers, large permanent puddles in the pavement are the typical aquatic habitats that produce mozzies. But don’t forget your bromeliads and the kids’ tyre swing, because they all can hold water. Lots of it.

There is some relatively good news for New Zealand gardeners. We don’t have the Australian salt-marsh mosquito which is a voracious biter and persistent follower of humans. We don’t have the Aedes species that can transmit a range of very unpleasant and lethal viruses and other mosquito-borne human diseases; nor are we at risk from malaria due to the absence of the Anopheles vector.

Yet our changing climate puts us more and more in the danger zones for these mosquitoes.

If you are lucky enough to live in a forested area with streams or rivers, waterfalls, lakes, wetlands and babbling brooks, you will probably familiar with the “sandflies”. These critters should really be called blackflies (the generally accepted vernacular name for Simuliidae), or better still, te namu. We’ve got about 20 native species

Clockwise from top left: Flea; Simuliidae black fly; and, Simuliidae black fly larvae on rock under water. Below: of these little devils in Aotearoa, but only three species actually bite humans. (Yes, I know that sounds incredible, especially when you’ve been for a tramp on the West Coast of the South Island or in Fiordland.)

Their feeding strategy is remarkably different from that of the mosquito. Blackflies crudely damage blood vessels close to the surface of your skin, creating a miniature pool of blood to which they add saliva and anticoagulants. Female blackflies literally lick up the pool of blood and cause a similar histamine itch, but without the elegant and precise phlebotomy we see in mosquitoes.

The little blackflies (about 2-3mm in size) are able to fly great distances from their aquatic birthplace, which explains why they are so persistent in following you down the track or in your garden, for that matter.

Have you noticed how blackflies often bite near the sock line or just under the cuffs of your long-sleeved T-shirt? This is a great example of quick adaptation by these insects that traditionally only had birds and seals to feed on. After all, humans didn’t arrive in Aotearoa until about 1000 years ago.

Penguins and wading birds have exposed, but also impenetrable, scaly legs, whereas their succulent “drumsticks” tend to be hidden under feathers higher up the leg. So all these little flies have to do is go under the feathers where it is nice and warm and the blood vessels helpfully accessible and dilated.

Females can lay eggs without a blood meal, but that batch is much reduced in size. A fully fed mum can drop hundreds of eggs in her lifetime and the perfect place to deposit them is on rocks and vegetation in a calm flowing stream. The larvae will sit there filtering and hence, cleaning the water that flows over the top. Next time you drink from a clear, remote stream in native bush, think about these little flies.

Gardeners tend to be exposed to a number of creepycrawlies that are able to bite or sting, especially during the summer months. With higher temperatures, conditions for cold-blooded invertebrates become more favourable: they breed and move faster, and get more numerous.

The complicating factors are a crepuscular habit and sometimes a poisonous defence system.

Nobody will voluntarily interact with a wasp nest for obvious reasons. These insects do not have a sense of humour and they will defend their territory with vigour and venom.

Some species of spiders can also cause some trouble, especially when they get trapped between skin and clothing. Weeding in dark places and lifting rocks and branches can result in an unexpected confrontation, but often the spider runs away quicker than you! Gardening gloves may be the solution to staying safe.

Some gardening correspondents complain having been bitten by ladybird beetles. Really? One of those cute beetles that eat aphids?

Of course, that’s a distinct possibility. After all, these predators do enjoy a bit of protein from time to time and

their habit of biting people is aggravated by the fact that some of their body fluids contain toxins (to deter predatory birds) that can cause some unpleasant reactions in a punctured skin. Nothing to be alarmed about, though.

In the North Island, we have some extraordinarily large, native centipedes (Cormocephalus rubriceps) that do need a little bit of attention. I’ve seen these predators up to 16cm in length, under rotting logs and below thick layers of mulch. They truly are the king of your compost bin, and the ruler of the nooks and crannies. Cormocephalus is also poisonous and it will inject you with its potion when it bites. I’ve experienced a case of two and a half hours of paralysis in hand and arm, followed by a few weeks of pain, followed by a few months of awkward and annoying itching. Believe me: don’t touch them!

In my list of invertebrate summer nuisances, I cannot overlook the yearly influx of fleas on the generic New Zealand carpet. In this case, it is the proliferation of hairy pets that is to blame.

Cat fleas and the less common dog fleas spend their larval life in your carpet, where they eat detritus and the excrement of adult fleas that slide off the pet’s fur. Pupation takes place in the aforementioned carpet, and the adult fleas tend to hatch during warm conditions and when they sense there’s a warm-blooded host walking around.

This little bit of information is of crucial importance if you want to explain why a cloud of fleas will greet you when you arrive home from a few weeks holidays: The pupal stage is the perfect condition to sit and wait.

When humans and pets return, their footprints and vibrations trigger a mass hatch of adult fleas, all looking for their blood meal. It is parasitic synchronicity from the days when felines returned to their favourite lair and canines lay down in their covered sleepout in the cool summer cave.

Yes indeed, there are sprays, oils, pills and droplets for these kind of calamities, some in the form of insecticides, others containing insect growth regulators. Take your pick!

Fleas are quite visible and you can feel them bite, but mites are a totally different story altogether. They are tiny and therefore impossible to detect, unless you are an entomologist and have good eye-sight, or, better still, own a good hand lens.

Biting, parasitic mites often spread from birds’ nests in your roof and march down to find some warm-blooded host. I know, because I muck around with young nestlings in my quest to band as many thrushes and gold finches, dunnocks, greenfinches, starlings and sparrows as I possibly can in my new-found (old) hobby of being a birdman.

The word “mite” can cause quite a few delusory psychotic reactions (think: dust mites in your pillow) so I tend to not use that word a lot, at home.

Mind you, an even better word is bed bug. But that’s a whole new story again and not necessarily appropriate for a summer edition of your favourite magazine.

A full fed mum can drop hundreds of eggs in her lifetime and the perfect place to deposit them is on rocks and vegetation in a calm, flowing stream.