QUESTION:

We have been spraying a home for years and the only problem they have is spiders. We have been spraying the outside with Temprid SC and the inside with Suspend. Most of the problem is outside. No lights are left on, it's a brick home with some vinyl. We also use the cob web remover and Delta Dust in some of the places. Is there something else I can use?

ANSWER:

I will maintain that the products you are already using should work perfectly for killing spiders IF the spider and the active ingredient are coming together in the same place while the a.i. is still present at a level sufficient to kill the spiders. I am not a great fan of assuming it must be the chemical, and therefore trying other products would not necessarily be the solution. In general spiders can be a difficult problem, but part of the reason is the terrible INtolerance most homeowners have for them. Even though most spiders are more or less harmless to people, and highly beneficial to have in our landscapes, the presence of a single spider is often enough to cause the customer to call you and tell you they are "everywhere" and you need to get rid of them. A much better solution, but a tough one to sell to Arachniphobes, would be to accept a tolerance of certain kinds of spiders. I know, I know....... easy for me to say and impossible for you to accomplish. But, it truly should not be our purpose to eliminate all living creatures around homes. To attempt this results in an excessive use of insecticides.

So, I don't think that switching to another insecticide is the answer, and perhaps you can gain a little relief by educating the customer, but if this is a lingering problem with many spiders on the structure then some other approach is needed. I don't know what frequency you are treating this structure, but it is unlikely that any insecticide today is going to leave an effective residual on an exterior surface for much more than 3 or 4 weeks, and even that may be optimistic. If you are coming quarterly then what you applied 3 months earlier is long gone and the spiders may have had the opportunity for a couple of months to approach this structure and climb onto it without being exposed to insecticide. Does this mean you should sell them on retreating every 2 weeks? Well, I'd hate to see that extra load of toxin added to their environment, so perhaps there is some non-chemical approach to look for.

Many spiders will travel through the air, via "ballooning", and will manage to get onto structures without having to crawl to them. These are unavoidable. But, most spiders are going to come from surrounding areas, so perhaps you can evaluate the property to see where you can eliminate harborage, not only to push spiders further away but also to eliminate many of the insects that the spiders have come for. Since you feel that exterior lighting is not the problem, it could be that at night plenty of moths of other insects still come to this home due to the INSIDE lights shining through windows, so the spiders still are making a good living on this structure. Eliminating this problem is probably impossible too - lights will be on inside, bugs will come to the windows, and spiders will recognize this food resource availability.

You could suggest creating a moat around the structure using gravel, crushed rock, or some other covering over the soil that is somewhat discouraging to wandering bugs. If shrubs are growing against the structure they need to be trimmed away, grass should be removed immediately adjacent to the foundation, and any materials stored directly against the structure should be moved away. This may not completely resolve the problem but at least helps that much more. I really think it is important for us ALWAYS to look for non-chemical solutions, as this is going to be the better long term control without the need for pesticide applications. The insecticides then supplement the other IPM steps, so I'm not on some anti-pesticide campaign.

Since the spiders seem rarely to be getting inside perhaps the occasional hunting spider found there can be sucked up with a dust-buster vacuum. Exclusion seems to be pretty good, but you still might find a few more potential entry points that could be closed. If the spiders are entering through attic vents then you could dust the attic with a desiccant dust that will last for a very long time and pose essentially no risk to people who do into it.

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