On Thu, 8 Apr 2004, Shirley Ellis wrote:

> I read through your response on pest control with great interest, as
> our Collection and others that I've worked in have had problems with
> carpet beetles.  Most recently we have had an occasional residual
> spraying done of the premises with a pyrethrin based product.  I'm
> curious to know why you are less comfortable with it than Gentrol?  I

Pyrethrins and pyrethroids can be sensitizers, and I'm one of the lucky
ones who's sensitized.  This can be a particular problem with someone
who's also a gardener, or who is also prone to allergy, asthma or
dermatitis, and it's especially likely in those sensitive to ragweed
pollen.  The usual problem is contact dermatitis, often made worse
with sun exposure, but a pretty stiff asthma attack is another
possibility.  Most pyrethrin preparations also have a synergist, usually
piperonyl butoxide, added.  This is to help prevent rapid enzymatic
breakdown of the pyrethrins.

In addition, when trying to control biological organisms, it's best not
to put your eggs all in one basket.  Sub-lethal doses of a pesticide
tend to select resistant members of the population -- they survive and
reproduce.  Resistance seems to be a particular problem with pyrethrins
and pyrethroids, much less so with IGRs.  Since the rest of the world
seems to use pyrethrins and pyrethroids more or less casually (check the
labels on insecticides offered for consumer use), I'm happier using
something else to help avoid resistant populations.

One of the problems with looking at toxicity studies with pesticides is
that the pure pesticide is not applied; instead, it's diluted with
solvents (the bulk of solvent for most IGRs is water), synergists are
added, and possibly also dyes, surfactants, etc.  The toxicity of the
whole preparation may not be the same as the toxicity of the active
ingredient.  We've certainly seen that with Roundup herbicide... the
active ingredient, glyphosate, causes little skin or eye irritation,
but there were numerous reports of skin and eye problems with Roundup.
When the "inactive ingredients" were changed, reports dropped quite a
bit.

As I said, I have not used Gentrol or hydroprene myself.  I have used a
couple of similar IGRs, methoprene and nylar, for household flea control
for a number of years without incident.  I've been considering using
hydroprene, as I've recently introduced an indian meal moth infestation
into my home kitchen, and it's labeled for this pest, but to date, I
have no experience with it.

In an active infestation in a museum, my personal choice for control
would probably be something that immediately kills the pests (freezing,
heat, quick acting pesticide), followed by something that breaks the
life cycle at a different point (e.g., an IGR), and stepped-up
monitoring.  Generally, integrated pest control programs are far more
successful than eggs-in-one-basket approaches.

Kay Lancaster  [log in to unmask]