Mosquitoes
13 January 2008
There are several hundred species of mosquitoes and six have found
their way to Hawaii. The first mosquito to arrive was the Southern
House Mosquito (Culex quinquefasciatus). It sailed across the
ocean with the Europeans in 1826. This was bad news to the native
birds which had evolved without
mosquitoes and therefore had a very low resistance to mosquito-borne
diseases such as avian malaria and avian pox. Of course it wasn't
exactly great news for humans either. The annoying little pests have
pretty much spread to every part of every island and they happily visit
every person they can find.
The Asian Tiger Mosquito (A. albopictus) came next in 1896. It
lives mostly in lowland areas and is a vector for dengue fever. There
is currently no human malaria or West Nile virus in Hawaii but
outbreaks of dengue fever have occurred as recently as 2001.
Inland Floodwater Mosquito (A. vexans nocturnes) arrived in
1962. It is not known to transmit diseases but it still bites plenty.
It's larvae can be found in puddles, ditches and other places that pool
water periodically.
The Bromeliad Mosquito (Wyeomyia mitchellii) and the Yellow Fever Mosquito (Aedes aegypti)
both arrived in the early 1980's. The Bromeliad Mosquito lays its
larvae only in bromeliads and cut bamboo while Yellow Fever Mosquito
lay larvae only in artificial containers. With such restrictions it
might seem easy to exterminate these mosquitoes until you stop to think
about how much bamboo and artificial containers there are in Hawaii.
The sixth mosquito species (Aedes japonicus japonius) became
established on the island of Hawaii in 2004. I promise it wasn't us
that brought it here. We didn't bring an coqui frogs, fire ants or any
other invasive species either.
Controlling mosquitoes is challenging. DDT was very effective with
little to no effect on humans but overuse of the chemical caused it to
be banned. DEET, found in many modern mosquito sprays, is a decent
deterrent. It doesn't harm the mosquito, it only discourages them from
biting. Citronella is not quite as effective and works by overwhelming
the mosquito's senses so it can't find you as easily.
Destroying breeding grounds is an important method of mosquito
control. A small piece of litter that collects as little as a quarter
cup of rain water can breed mosquitoes in as little as three days. It
doesn't have to be trash, it could be a puddle or a leaf. We try to
get rid of any standing water around the farm but it doesn't take much.
Of course we have screens on all our doors and windows but mosquitoes
still find their way into the house. It doesn't help that the dogs and
cats think of screen doors as unfair obstacles and happily claw their
way through, creating a dog sized hole in the screen. I recently
purchased several heavy duty metal pet guard screens then spent a day
fixing all our broken screen doors. We'll see if that makes a
difference but I'm not going to hold my breath. I'm resigned to the
fact that you can't live in the tropics unless you can deal with a few
mosquitoes.
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