QUESTION:

I have a client with fleas but she does not have any pets and has had a home inspection to determine if there are any rodents trapped or dead inside of her chimney, walls, etc. She has the occasional cats (not hers) walking around the house outside, but it has been that way for three years with no issues. We have treated the home twice and she has indicated that the living areas are virtually free of fleas. However the basement has now become their home. I've used Demize as well as Transport GHP and she seems to think that the Transport GHP has worked the best. Do you have any idea as to where they might be coming from? Any suggestions of what else to use?

ANSWER:

A couple of observations or thoughts to start. First is that those outdoor cats could suddenly become the source of a flea infestation even if they were not creating one in the past. It is a matter of the cats themselves acquiring fleas from some other source and now carrying the fleas around on their bodies, shedding flea eggs wherever they happen to spend time. However, this should not account for a lot of fleas indoors if the cats stay only outdoors. What normally will happen, though, is that feral cats or wild animals such as raccoon or possum will find a way to live under a house or an adjacent deck, seeding the soil there with thousands of flea eggs over time, and the ensuing adult fleas can find their way into the home. I have seen this twice recently with major invasions of bathrooms in homes where the source was the crawlspace below or the soil under a wooden deck immediately outside.

Aside from those thoughts we know that fleas must come from a vertebrate host animal. The typical flea is the Cat Flea, and it is a permanent ectoparasite, meaning it prefers to remain on the host animal and does not readily hop on and off. But, the eggs fall of the host animal and the larvae live independently in carpets, on soil, or any other protected substrate where they can find food, and one part of their food must be dried fecal pellets of blood produced by adult fleas. These also fall off the host animal along with the eggs. So.......somewhere nearby you must have some location where host animals have been spending time, and this is important to locate. We would consider this to be the source of this problem, even though the adult fleas may be found some distance from the source, as they will move about looking for a new host animal to get onto.

Since this seems to be a lingering problem in the basement you either have continuing production of flea eggs coming from host animals that are resting, sleeping, living nearby, or it is the vestiges of a flea problem that occurred there but still is not gone. Your enemy in flea control is the flea pupa, as the flea that has developed within the pupa can remain there for a very long time - many months - waiting for the proper "stimulus" that signals that a host animal (food) is nearby. This may be physical contact or strong vibration. To get these last fleas out of that pupa and into the exposed adult stage you can recommend that this customer THOROUGHLY vacuum every square inch of the basement before you treat again, and if it is carpeted to vacuum again each day for the next week. You might even have her vacuum the upper living areas again just for the heck of it.

The products you have used should kill adult fleas just fine, but the Demize is more of a short lived contact product that provides little residual. Better might be a residual material such as the Transport or some other pyrethroid that will last a couple of weeks to affect new adult fleas. It also is important to use an IGR with the treatment. The growth regulators are terrific products that can mess up both flea eggs and larvae so they do not develop properly, and if you stop getting new adult fleas you break up the life cycle. The IGR can be applied along with the adulticide, and should last up to 6 months.

Without physically visiting this home and seeing the basement and configuration of the building it would be hard to know just where the initial host animals were living to begin this infestation. It's possible those animals are still living around the home and continuing to seed the area with new flea eggs, or it's possible this is just the remnants of an old infestation and the pupae that have not yet hatched. Take a fresh pair of eyes in there and look at that basement and the areas outside it to see what you can find. You might find a lot of those outdoor cats residing comfortably under some bushes or a deck or some other cozy place right outside the basement, and if so they should be discouraged.

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