QUESTION:

How do you effectively control mosquitoes at schools? I am having a problem applying pesticides due to children being in close proximity. Thank you.

ANSWER:

Rightfully so you are concerned about the use of insecticides on school properties, for nearly every state has regulations in place regarding school pesticide use, and your state of Arizona is no exception. Like most states with respect to K-12 schools as well as day care centers there are notification requirements, posting requirements, record keeping requirments, and a requirement that these schools and day care centers have in place a specific IPM program. I suggest you begin by working with these schools to ensure they are complying with all of these requirements, and for Arizona and all other states you can go to PestWeb for help. Look in the "Business Tools" tab and then IPM in Schools, and you will find your state and links to the specific regulations in place.

There also are "exemptions" to these regulations depending on what kind of pesticide you use, and for mosquito control in Arizona one exemption is for Public Health uses with "non-residual" insecticides. You still need to ensure the school does the notification to parents and employees, but it can be done "post" application if necessary. Refer to your state's specific laws on this to determine what is needed. For mosquito control we could divide it into either larval control or adulticiding, and this makes a lot of difference in what you may be required to do. Adult mosquito control is the least effective, meaning what you kill is a temporary relief. Fogging for the mosquitoes using pyrethrum will put you into this "exempt" status but give relief only for a day or so. The use of residual insecticides for "barrier" treatments will give much longer adult mosquito control, but it also puts you into the full regulatory requirement of pre-notification, posting, etc.

Control of the sources of the mosquitoes, meaning control of the larvae directly in the places where they are breeding, is by far the best form of mosquito management. Since you are in Arizona these sources ought to be somewhat limited, and I suggest carefully determining just where these mosquitoes are coming from. It may be that there are some temporary water sources that could be eliminated entirely. It could be small water sources such as catch basins or local ponds that could easily be treated with biological larvicides, and these products should be exempt from much of the School Pesticide use requirements. Eliminating the larvae obviously also prevents adult mosquitoes, and if you can prevent the biting adults you no longer have to take the fly-swatter approach of trying to kill the flying adults before they bite people.

If you choose to go with fogging with pyrethrum your best timing would be just prior to events where people are going to be outdoors during adult mosquito activity times. Again, this gives only temporary relief, and more adult mosquitoes could quickly replace those you kill. Barrier treatments involve the application of residuals such as pyrethroids to adult mosquito resting sites - trees, shrubs, under eaves and other shaded locations where the adults rest during the daytime. These can be very effective if you manage to apply the products to the proper places, but since they are residual materials they would require the notification and posting, and this might be a stumbling block at some schools.

Along with all of this, of course, is the recommendation that you ensure these actually are mosquitoes. Many times people will be seeing similar gnats, such as crane flies or midges, and believe that they have mosquito problems.

View past Ask Mr. Pest Control questions.