A theory: please don't water the mites

[Guest guest]

I don't know if this is new, but I had an idea that may explain why

some people are having such a hard time getting rid of the mites. If

true, it also suggests a strategy to eliminate them.

The theory is based on the following three premises:

1. Mites require water (or high humidity) to allow them to live a long time.

2. Many mites hide in small cracks or hard-to-clean places, especially

when there is light. Thus, they are inaccessible and cannot be killed

by the normal actions (such as washing or applying chemicals) that

people try.

3. Many of the actions people take to control mites use water which

evaporates and thus increases the humidity. Examples include steaming

or washing carpets with hot water, applying salt water, applying

Windex (which is mainly water), steaming or soaking clothing, taking

long hot showers.

The theory is this: The actions people take to control mites can't

kill them all because most are hidden in inaccessible places.

However, these actions increase the humidity which allows the mites to

live longer. It's like trying to kill weeds by watering them. As

long as some mites live, all it takes is a few to feed, and they can

lay eggs and start another generation.

So here is the proposed strategy. It relies on two goals:

Goal 1. Reduce the mite life-span by creating a low humidity and high

temperature environment.

Goal 2. Break the mite life-cycle by preventing mites from feeding.

How to achieve goal 1 (reduce mite-life span).

1. Minimize activities (mentioned in premise 3 above) that will supply

the mites with water or increase the humidity. That is:

a. Don't steam or vacuum using water; don't spray the floor or walls

with salt water or Windex or alcohol (all contain water which will

evaporate increasing humidity).

b. Don't soak clothing in open containers which allow evaporation.

If you soak clothing, do so in a way that will minimize the increase

in humidity. Soak in a closed plastic bag or other container.

c. When you take a shower, try to do it in such a way to not

increase the humidity very much. Perhaps after getting wet, spend

most of the time lathering and scrubbing without the water running,

then rinse. If the steam from your bathroom is going into the house,

try not to have hot water running a long time which produces steam

(humidity) helpful to the mites. Or if you have a fan in the bathroom

or a window, use them to divert the steam that would otherwise go into

the rest of your house.

d. In short, don't do anything that will substantially increase the humidity.

2. Buy a dehumidifier and run it all the time. Strive for a humidity

of 30% or below. Tips: the June 2008 issue of Consumer Reports

magazine has an article about buying dehumidifiers. You also might be

able to find a used one. I bought a used dehumidifier through

Craigslist for $30.

3. Turn up the heat on the thermostat to 80+ degrees.

Overall goal: turn your home into the equivalent of a HOT ARID DESERT!

WHY THIS IS IMPORTANT:

=============================

For supporting documentation, goto this page:

http://www.asg.wur.nl/UK/research/projects/AnimalHusbandry/Programm/

Then click on the first link " Biology, vector-potential and life cycle

of Dermanyssus gallinae "

Or click here:

http://www.asg.wur.nl/NR/rdonlyres/C46DBE42-73CD-45FF-B35B-3473D06BBE03/34480/Li\

feCycleIssues.pdf

It will download a 1.2MB PDF document.

Then look at the graph labeled: " Longevity in different temperatures

and RH% " (fifth page in document)

Note the following:

TEMPERATURES:

At 25 degrees Celsius (77 degrees Fahrenheit) mites die off in 5 weeks.

At cooler temperatures, they live for 40 weeks.

Thus, HOTTER IS BETTER because it kills the mites.

HUMIDITY:

At 30% relative humidity or below, mites die off in 5 weeks.

At high relative humidity, they live 20+ weeks.

Thus, DRYER IS BETTER - again, because it kills the mites.

=============================

Again, you want to create a HOT, DRY environment to shorten the mite life span.

Incidentally, the second link on the above page links to a document

(also should be able get by clicking here):

http://www.asg.wur.nl/NR/rdonlyres/C46DBE42-73CD-45FF-B35B-3473D06BBE03/34485/Ve\

ronikaMaurer.pdf

called " Behaviour of Dermanyssus gallinae " which describes how the

mites hide in small cracks during the day and tend to feed at night

(this supports premise 2). They are also attracted to slight

temperature gradients (warmth, possible source of feeding), which

maybe means they will try to crawl into your bed when you sleep if

they can. The document also has a great close-up picture of a mite

(D. gallinae).

==============================

HOW TO ACHIEVE GOAL 2: (break mite life cycle by preventing mites from feeding).

Note: There are multiple approaches; the following is what I did.

1. Make sure this is no more original host (birds nest or whatever).

2. If you have carpet, vacuum it often using a dry vacuum (not

steaming or water).

3. If you have bare (non-carpet) floors, clean frequently, but either

dry vacuum, or try to use minimal water when washing and mop it up

right away to minimize evaporation.

4. Sprinkle Diatomaceous Earth (DE) or Boric Acid on cracks or places

where the mites might traverse.

5. Spray walls or other surfaces that mites crawl on with an

insecticide which works for mites. (I didn't do much spraying, only a

small section were I was constantly seeing them).

6. When sleeping, it's critical to prevent the mites from biting you

during that time. I take the following steps:

a. Encase mattress and pillow in plastic cover (I bought mine at a

dollar store).

b. Use minimal and synthetic covers (one or two blankets) and

synthetic sleeping clothes which are frequently washed and dried in a

HOT dryer, ideally just before sleeping. (Minimal covers are OK

because you won't need much covers since the air temperature will be

80+ degrees).

c. Buy a 12x9 foot plastic " drop cloth " (plastic sheet) from a

dollar store ($1) or someplace else (hardware store) and fold it so it

drapes over your mattress and bed, hanging over the side of the bed

(but not touching the ground), so that any mites crawling from the

floor up onto your bed would be under the drop cloth and thus not able

to get to you. I THINK THIS IS VERY IMPORTANT. YOU NEED TO PREVENT

THEM FROM CRAWLING FROM THE FLOOR TO WHERE YOU ARE IN BED.

d. Shower before going to bed to try an wash off any mites that

might be on you.

e. After showering, and drying before you go to bed, put plastic

bags over your feet before walking from the bathroom to the bed so

mites don't get on your feet when you are walking too the bed. Get

into bed carefully so any mites on the plastic bags will not be

transported into the bed. (I'm not sure if this is really important,

but I felt safer doing it.)

7. Frequently wash clothing and bedding (and if possible, shoes) in

hot water and (more importantly) dry in a HOT DRYER. Store in plastic

trash bags until ready to use.

My apartment was infected with bird mites (from microscope images, I'm

pretty sure they were Dermanyssus gallinae - the hard species to get

rid of) about two months ago. Before I knew what was going on, I had

lots of bites and was seeing mites everywhere. Following the above

procedures, I think I've wiped them out. I'm not sure, since some

people said that the eggs can reinfect. But so far things look good.

One reason I think minimizing the humidity is so important is that I

captured some mites and put them in cups with plastic over the top,

but with no water. I captured some others and put them on a island

(small object) which I placed in the middle of a tray of water, with

the entire tray sealed with plastic over the top (to hold in the

moisture from the water). After a week, the mites that were in the

cups without water died. Under a microscope, I could tell they dried

out. The mites that were placed on the island with the surrounding

water all lived. A dramatic difference. The water moisture (high

humidity) enabled them to live while the others without the water

died.

I might have had a much easier infestation than what others have had.

Everyone dealing with these mites has my deepest sympathy. I hope

this is helpful to some of you. Don't give up. Fight on!

Jeff Teeters

Berkeley CA