Wasps can be a problem for many reasons. In addition to an unpleasant human interaction, wasps like to build nests in confined spaces such as in gill-type temperature shields. These nests block airflow and cause elevated temperature readings. Several steps can reduce wasp nests. First, we have found that plugging all open tubes reduces nests in the end of the cross arms We have found that the short vinyl caps from either http://stockcap.com or http://www.caplugs.com work well to fit snugly over ends of cross arms. If the caps are a bright color, this has the added benefit of high visibility to prevent head bumps. Another effective method to plug tube openings is to put closed-cell foam inside the hollow cavities of cross arms.
Once possible nest locations are reduced, it helps to use spray repellent. Some sprays kill wasps and the residue will linger and prevent wasps from returning. Gill radiation shields can even be sprayed with repellent. While this residue can be washed off with moisture, it still helps.
We have used traps to reduce wasp populations around a station. Traps use an attractant to lure in and trap wasps. This is an effective longer-term solution instead of – or in addition to – spray repellents.
Passive, gill-type temperature shields provide a cavity in which wasps like to build nests. We have found that MetSpec temperature shields have reduced numbers of wasp nests, apparently because the gaps that wasps would use to enter the shield are smaller, making it more difficult, for them to enter. Wasps do not like to build nests in areas that are windy. In our experience, wasps never build nests in aspirated temperature shields.
Getting good data goes far beyond sensor and product selection. Ongoing maintenance, such as checking a gill shield for a wasp nest, is critical to gathering good data. We consistently remind our customers that ensuring sensors are mounted correctly, leveled when needed and cleaned periodically go a long ways to getting better measurements.
Product Development Scientist