What is the best way to treat for Eastern Sand Wasp? They are in the sand of a playground. -Richard, OH
The combination of limited ways to deal with sand and soil burrowing bees and wasps, plus the sensitive nature of a children’s play setting, make these a difficult problem to address. Hopefully, although I’m sure I’m being overly optimistic about it, parents and others who oversee this playground will gain some level of tolerance for these wasps. The several kinds of wasps that burrow into sand to create chambers for their larvae are solitary wasps, and there is very little reason for them to sting anyone unless they (the wasp) feels directly threatened. There is no queen, no “colony”, no social structure, and no instinct to rush out to defend the place they are working. If someone grabbed one of the adult wasps in his hand, or got one trapped in their clothing, then the wasp may sting in an effort to escape, but otherwise it just doesn’t happen.
The adult female wasp digs the tunnels when the sand or soil is of the proper consistency to hold up for it. If the sand is too dry it should keep collapsing as the wasp digs, and this is going to cause it to go somewhere else to find a more appropriate place. This is non-chemical step #1 in management – maintain the sandy play area in a dry condition, and if sprinklers are getting it wet they should be re-aimed to avoid that area. If it is rainfall keeping the area damp then you have no control over this option. The wasps are predators, and the female captures other insects, such as crickets, grasshoppers, caterpillars, etc., to place in each chamber for her larvae to feed on. Obviously this is of benefit to us, and gives a good reason for preserving these insects if possible. The period of time that the adult wasps will be working the area should be fairly short, so the problem also is self-limiting. It may be possible, if the sandy area is fairly small, to cover it with black plastic to heat up the sand as well as to prevent the wasps from getting to it at this time. Long term it may also be preferable for the sand to be replaced with some other substrate, such as recycled tires or bark, which the wasps will not use. If this is just sand around play equipment it may be serving only as a soft landing area.
All of this is an attempt to find the long-term, non-chemical solution. There are insecticides that might be repellent or might kill the active adults as they dig, but there are plenty of people who have serious concerns over ANY pesticide and any contact their children may have with it. Applying a “toxic” substance to the sand their children play on will likely trigger some complaints, and likely cause some parents to blame any health condition their children then come down with on their exposure to what you applied. This could be mitigated somewhat if a “natural” product is used, such as a plant-derived insecticide. The problem is that most of these are very short lived, and you may have to face constant applications to get positive results. This is the reason to search for that non-chemical solution where possible. Depending on the laws in your state you may even be required to post the area you treat with pesticides, and this sets off alarm bells in the heads of many people who have strong fears of pest control chemicals.
I would discuss this with whoever is responsible for this play area, and encourage them to change from sand to some other substrate that serves the purpose but does not attract the wasps. If the sand must remain see about covering it with plastic to create the physical barrier during the wasps’ digging season. Treating each hole individually with an insecticide may be effective but probably is impractical, and even this kind of selective treatment is going to cause concern for parents. After all, their children are digging there too. Dust products would work the best but are far less likely to be effective once they get wet. If a botanical product turns out to be acceptable to everyone then consider a product like EcoExempt IC-2, which should even provide a week or so of residual, although how effective it will be on the wasps that land on the treated soils is something I do not know.