New Zealand, Canada and many other countries abound with the world's
finest natural scenery. They have glaciers, lakes, mountains, rivers,
stunning harbors and a healthy population of sandflies.
For those that have yet to meet the sandfly they are a small black
gnat like creature with a humped back. Traveler blogs refer to the sandfly
as "hated, filthy, and annoying." Scientists often downgrade
the sandfly to a "nuisance" category only because it is rare
for anyone to die from a sandfly attack. Still some medical literature
refers to sandfly bites as causing-
· Acute discomfort,
· Irritation, and
· Severe local reactions
In the last few years many advancements have been made in managing
travel in sandfly prone areas. With a little forethought and planning
we can fully enjoy the natural environment while living in harmony with
the infamous sandfly.
Sandflies typically arrive one or two at a time. They quickly build
to a swarm encircling the victim. They seek exposed skin where the female
saws a hole through the outer derma with a mouth shaped like a bread
knife. Bleeding begins and a collection of blood is formed.
The sandfly drools while it laps up the blood pool. This drool contains
a powerful anti coagulant called histamine that prevents the blood from
clotting. Agglutinins that prepare the pooled blood for digestion are
also deposited on the skin. It is this histamine and agglutinins mix
that causes the red bumpy reaction in the victim's skin.
Amazingly sandflies tend to feed on tourists and new arrivals while
locals seem to build some type of internal resistance to sandfly bites.
It may be that locals receive the same number of bites, but their body
has built a resistance to the histamine reaction. It is this resistance
that allows some people to remain unaffected by the sandfly bites while
others swell with red puss filled sores.
Sandfly defense plan
Sandfly swarms can arrive quickly. By building a sandfly defense plan
a sandfly swarm can be made tolerable. The plan should contain clothes
that are instantly donned and actions that are taken.
A sandfly defense kit should contain-
· A hooded sweatshirt
· Pants that can tuck into socks
· Bug repellant
· A hat that has bug repellant applied
· Close up the boat, camper, and car.
· Take care of the kids
· Light the citronella candles
Ten Sandfly defense tricks
1. Wear a hat covered with some type of sandfly deterrent. Goodbysandfly,
tea tree oil, eucalyptus oil and citronella oil all have had success
in repelling sandflies.
2. Consume vitamin B. This defense works for mosquitoes and sandflies
alike. Vitamin B capsules, Marmite, Vegemite, and brewers yeast all
contain high levels of vitamin B that will considerably help in deterring
sandflies. The effects of vitamin B can most easily be seen when standing
with a group of non-vitamin B eaters.
3. Bug protect your anckles with socks or some bug repellant. Sandflies
tend to start their attack at the ground level and work upward.
4. Wear light colored clothes. Sandflies are attracted to dark clothes.
5. Walk. Sandflies are very slow creatures. As long as you are moving
they can't swarm.
6. Keep your car, caravan, and boat closed up. Sandflies are notorious
for their ability to find openings to enter and lie in wait.
7. Boat's can anchor offshore a short distance to minimize the sandfly
8. Plan the day to spend sunrise and sunset geared up for sandfly defense.
9. Sandflies are attracted to heat. Turn off needless lights during
10. Sandflies can follow a carbon dioxide trail hundreds of meters.
If dense bush is located directly downwind consider moving.
Color of clothes
Testing has shown that light colors don't attract sandflies nearly
as much as dark colors. Becky Cashman of http://www.goodbyesandfly.co.nz/
a producer of natural sandfly repellent says, "The single best
defense against sandflies is to cover up with light color clothing."
This is because sandflies close in on their prey by use of built in
infrared sensors. White does not reflect as much heat as dark colors.
Wearing white clothes can be especially effective if others are wearing
dark colors nearby.
What to do when the sandflies are in your camper or launch
Sandflies have an uncanny way of filling empty areas. Opening the door
to a living space can allow dozens of sandflies to enter where they
will lie in wait till dusk or dawn to feed.
Sandflies make no noise when flying so a stealth dawn assault is inevitable.
This is important as a sandfly attack while you sleep can produce over
a dozen bites in a single morning. Over a week this can add up to a
lot of red itchy bumps.
Segregate the living space
The first defense is to segregate the living space. Hanging mosquito
nets between cabins helps reduce the spread. A mosquito net draped over
a hatch, window, or door allows easy access, but prevents most sandfly
entry. A mosquito bed net is an elegant solution for a peaceful nights
Quick sandfly eradication
Luckily sandflies are attracted to heat. A simple method of clearing
sandflies from a living space is to turn on a single light. Force the
sandflies into the air by walking through the cabin swinging a duster
or magazine. Pay particular attention to the corners, and areas under
The airborne sandflies become attracted to the light and begin to circle.
As the sandflies surround the light they become easy pray for a quick
smash against the light housing.
Citronella oil repels and even kills sandflies. Citronella oil lamps
placed upwind can help to deter a sandfly attack. Citronella candles
burned inside the vehicle or cabin a half hour before entry can kill
most of the errant and hiding interior population. Remember to keep
an eye on the open flame.
Opening back windows and taking a drive can suck the errant sandflies
out of a vehicle or boat. Sandflies don't like heat. Closing up a vehicle
or boat in the sun for a short period can kill the complete invasion.
Bites and how to deal with them
The first step to managing a sandfly bite is the application of an
antiseptic. Goodbysandfly states,
Essentially your are dealing with three separate things-
· A protein in the saliva of the sandfly
· Any contaminants that the sandfly introduced to you via
· A small wound.
Early cleaning and disinfectant goes a long way in reducing healing
time. Becky even recommends the natural remedy of a bit of onion juice
rubbed onto the bite as a way to reduce itching and healing time.
Another common herbal remedy for reducing the itch of bites is Chamomile
tea, drunk as a tea or applied topically.
Squeeze or not
Some tourists claim it's better to squeeze the toxins from a bite.
To find out I tested two bites side by side. One I squeezed once to
remove the toxin while the other I left to it's own devices. Over the
next few days it looked as if the closed wound would heal quicker, but
by day seven the squeezed bite was looking cleaner. On day ten both
bites healed completely.
Our in field testing dictated it was best to leave the bites to their
own devices so the wound remains closed reducing the risk of infection.
New Zealand South Island sand fly population
While all coastal and river areas can be affected by the dreaded sandfly
the most active concentrations are found along the west coast of south
island and Fiordland. These areas also contain some of the most spectacular
scenery to be found in New Zealand.
The sandfly density typically has a slight reduction in numbers during
July and August. Sandflies tend to be the most vicious on cool, windlass
days just before dusk especially near dense bush or stands of trees.
Sandflies thrive in humidity above 60%. Thus, we can expect sandflies
to swarm just before it rains. Hot, dry days are nearly sandfly free.
To the traveler this means pay particular attention to the weather
for predictions of overcast calm days with high humidity meaning it's
time to take full sandfly precautions.
The incredible sandfly life cycle
D. A. Craig, a retired entomologist and renowned sand fly expert is
currently studying sandflies in New Zealand. He explains that New Zealand
has 18 sandfly species. Luckily only three species bite humans while
the rest feed on penguins, bats, and other local animals. Of the three
species that feed on humans only the female bites while the males feed
in shady areas eating sap, nectar and other vegetarian meals.
The female wants to ingest blood in order form eggs. Without a blood
meal a typical female can only lay a dozen or so eggs. Once the sandfly
has eaten a full blood meal they can lay up to three hundred eggs two
to three times in their life cycle. In other words a single female sandfly
can produce nearly a thousand offspring. This helps explain the sandfly
The sandfly copulates only once in a lifetime storing the male seed
that re-fertilizes each new batch of eggs. The eggs are laid in running
water clinging to mud, rocks or vegetation. Sandfly eggs take about
ten days to hatch into small larva.
The newly hatched larva attach themselves by hooks on their bums to
vegetation or rocks in calm flowing water. They extend a set of fans
that filter the flowing water witch they feed upon.
Once fed, the larva forms a cocoon of silk where the larva, like a
butterfly, soon becomes a sandfly. When the sandfly morph's or "hatches"
from its cocoon it forms an air bubble. The adult sandfly enters the
air bubble, rises to the surface perfectly dry, and flies away seeking
Early Maori and settlers were plagued by sandflies. In defense some
rubbed their bodies with rancid bacon fat, while south island lighthouse
keepers painted their doors with kerosene. The Maori repelled sandflies
with a mix of crushed leaves from the Ngaio Tree while some doused their
bodies with Red Ochre.
In 1892 the Minister of Public Works smeared himself with camphorated
lard, which he claimed worked well. Some ancient lour even reports early
settlers actually swallowed a teaspoon of kerosene claiming the oil
would ooze from their pours repelling sandflies.
Once bit Maori applied a juice from crushed Ngaio leaves or a juice
made from the fronds of Rarauhe or Bracken Fern.
Future of Sandfly defense
Technology is helping the tourist enjoy his New Zealand experience.
From new types of repellant, to electric bug zappers, advancements are
made almost daily. Here is a selection of the latest innovations.
Insecticide clothing sold at www.insectshield.com now claims the first
insect repellent apparel registered by the U.S. Environmental Protection
Agency. BUZZ OFF contains permethrin, a man-made form of an all-natural
insect repellent derived from the chrysanthemum plant.
Light manufactures are now designing bulbs that give off yellow luminous
pigment that is reputed to repel insects, especially insects that are
attracted to light. See http://www.tradenote.net/mosquito_2/
High-pitched noise has helped to repel insects of all types. A variety
of manufactures now produce portable noisemakers just outside of the
human ear response. They report a distinct reduction in insect swarms.
High voltage bug zappers are now common, with a portable tennis racket
style available for those that wish for an interactive bug eradication
Fine mesh helmets similar to those used by beekeepers are available
to those who must continue to work in sandfly-infested areas.
As a last resort one can always fold up this magazine and swat the
sandfly into oblivion.
Special thanks to Douglas A. Craig, Professor Emeritus, Department
of Biological Sciences, University of Alberta, Edmonton, and Becky Cashman
D. A. Craig, is currently in New Zealand with Landcare research studying
sandflies. The last sandfly revision was done over thirty-five years
D. A. Craig poses three sandfly mysteries-
1. How do sandflies find there pray so far from breeding grounds?
2. What did the sandflies eat before humans arrived?
3. Are there more sandflies today than pre-human times since sandflies
now have such a handy source of food?
Sandfly density can overwhelm local cattle due to anaphylactic shock.
Even the human population is not immune. In Canada for example trade
unions have negotiated into their contracts clauses that prevent work
when sandfly densities reach epidemic proportions.
New Zealand sandflies don't carry any known diseases that effect humans.
They do however carry a form of bird malaria that affects penguins.
Goodbysandfly reports it's better to open an upwind window in a living
space. If you open the down wind window sandflies collect in the eddy
created and enter the space. Simple net curtains can do wonders for
keeping an inside space comfortable.
Sandflies are particularly susceptible to insecticides, but spraying
has not seemed to reduce their population. One report from Columbia
sent scientists to local homes where the inside walls were sprayed with
insecticide. Test traps collected in the homes showed almost no reduction
in sandfly population. It was thought the density of sandfly population
in the bush was so great that they simply "re-filled" the