Mowing Grass After Spraying

October 4, 2011, by Debra Lynn Dadd

Question from Annette

Hi Debra, Our neighbor had Orkin come on Saturday, September 24 to fog, not spray, for mosquitos with Talstar Professional. They have a lot of property and part of their property goes behind our back yard. Now, since we have complained of reactions they don't fog towards our house now. But it still drifts because we still have reactions. Which means it probably drifted onto our grass.

Now it has rained a couple of times since then.

Now with me having MCS, my husband has MCS as well and so does our daughter, my question is, how soon can we get out and mow the grass and do some weedeatting around the house and yard and do this without having reactoins since they fogged for mosquitos next door? Thank you very much for the help.

Debra's Answer

Talstar contains bifenthrin, a pyrethroid insecticide that affects the nervous system of insects. 

It is virtually insoluble in water, so it has high persistence in soil with a half life between 7 days and 8 months. It lasts longer than any other termiticide currently registered on the market.

Pesticides containing bifenthrin have been withdrawn from use in the European Union.

So, in terms of mowing the lawn, if there is any Talstar drift, it's going to be there a while. Half life is "the time when the expected value of the number of entities that have decayed is equal to half the original number." It's a probability, not an absolute. So minimum time before it will be gone is 14 days, and would probably be completely gone in 16 months.