By: Robert A. Dunn, Department of Entomology and Nematology, University
of Florida - IFAS

Fleas are bugging a lot of people and pets! The common "cat flea" (the
same flea attacks cats, dogs, and our ankles) seems to be everywhere
this year. Recently, consumers, pest control firms, and veterinarians
all have raised questions about new flea-control products that are based
on an insect-parasitic nematode. Some registrants' claims include "One
application lasts up to four weeks;" "95% mortality of the immature flea
within 24 hours;" "Will not harm humans, pets, or beneficial insects."
How well do these claims hold up? Can these good-guy nematodes provide
pets and their owners the promised relief from the pesky populations of
flea larvae that infest soil and turf around homes?

First, safety: The insect-parasitic nematodes being marketed for flea
control are, indeed, safe. They are not the nematodes that attack
people, pets, or plants. They are limited to certain kinds of insects,
and have also been found to be effective biological control agents
against several other kinds of insect pests that live in the soil.

As to their effectiveness, there is no clear-cut answer. There certainly
is not enough research under Florida field conditions to justify an
unlimited recommendation for their use. Results of trials done under
artificial conditions in North Carolina, California, Texas, and
Louisiana have been very promising. They sometimes have provided more
than 95% control of flea larvae in carefully prepared soil mixes.
However, they were much less effective in several preliminary trials
conducted in Florida.

In Gainesville, Florida, applying this same nematode to turf plots
similar to many lawns did not reduce the numbers of adult fleas that
emerged during the following 10 days. In laboratory experiments designed
to determine what might have caused the nematode treatment to fail, the
effectiveness of the nematodes was strongly influenced by the relative
amounts of sand and clay in the soil, and how wet it was. Nematodes were
most effective against fleas in moist sandy soils. Those are conditions
in which fleas survived most poorly whether treated with nematodes or
not, and also the most favorable conditions for nematode survival and
activity. Flea control with the nematodes was least on natural turf and
best on bare soil surfaces which had adequate moisture.

Further research is clearly needed to reconcile the differences in
results from Florida and some other areas. For now, these nematode-based
products may give consumers a chance of acceptable control of fleas in
the landscape when they are applied exactly as directed by the
manufacturer. The nematodes may fail in some environmental conditions
common in Florida (especially dry locations such as lounging areas under
shelter of buildings). They may not reduce flea populations as
completely as some chemical treatments. However, many consumers will
consider it real progress to be able to reduce flea populations in their
exterior premises with an environmentally benign product. Of course, to
achieve the best flea control, infested indoor areas and pets must also
be regularly treated as recommended by animal health care professionals.

http://ipm.ifas.ufl.edu/applying/met...nematode.shtml

My own comments on this article....

I'm convinced that nematodes are one of the best ways to deal with fleas
and not use pesticides. However, they do have limitations and most
websites that sell them don't tell you enough about the conditions
needed to make nematodes work.

My comments will specify their viability in Florida since that is where
I live.

The article goes over soil, moisture and other conditions that are
needed for nematodes to work their best. One point they did not cover is
that it matters what you've been putting on your yard before the
nematodes because some things can hurt them. After all, you are dealing
with living organisms.

Pesticides, diatomaceous earth, even tobacco dust can hurt the nematodes
so you have to take into consideration any of these if formerly applied
to the yard. DE of course melts away in rain so it's really not an
option in Florida in the summer and I would think that the yard would be
clear of DE rather quickly.

The nematodes need moist soil to live best and would be perfect during
the wet summer months. The article also mentioned that nematodes like
sandy soil best, and much of Florida is sandy.

There are also temperature considerations. Nematodes like temperatures
of 40 and 90 degrees, again, perfect for Florida summers.

Because nematodes like it damp, once the rainy season is over the yard
will have to be watered now and then to keep them going.

I've personally never used them but plan to. Is there anyone with
experience with nematodes that would like to share?

Char