Careful Consideration

Editor’s note: This article originally appeared in a PCT e-newsletter titled “Smart Exclusion Solutions,” which was sponsored by Xcluder.

Before selecting materials that will be used in an exclusion service, PMPs should consider factors such as type and size of the opening (door, utility, etc.), environmental conditions (nearby a dumpster or moisture), pest pressure, the scope the service (pricing), and expertise of the service professional doing the work. These key factors in successful rodent control were explained by Dr. Matt Frye, a pest management specialist with the New York State IPM Program at Cornell University, in an educational session at NPMA PestWorld 2017.

Other considerations include function and permeability. Weatherization materials, for example, are not necessarily pest-proof, as chewing through the product can compromise expanding foam, explains Frye.

In addition, some spaces, such as attics, eave vents and weep holes, are designed to allow the structure to “breathe” to avoid moisture problems and degradation of the structure. In these cases, Frye explained, the correct materials will seal out pests but still permit required airflow, ensuring the structure stays dry.

Once these and other factors are taken into consideration when servicing an account, pest management professionals then need to determine which materials will be the longest lasting and most effective in a particular situation.

Frye also provided the following helpful hints for implementing a pest exclusion program:

• Stainless steel metal mesh fibers are abrasive for chewing rodents and they do not rust. Simply use a probe to push in the mesh and fill the gaps.
• Escutcheon plates can be moved by pests, so they must be properly sealed to the wall. Measure to obtain the right size and use and the correct elastomeric sealant.
• The terms “caulk” and “sealant” are sometimes used interchangeably, but they are actually two different things. For a complete guide describing the best way to choose a sealant, refer to “Recommendations for Selecting and Using Caulks and Sealants in Pest Management Operations” by Bobby Corrigan, RMC Pest Management Consulting.
• With hardware cloth, size matters (19-gauge ½- by ½-inch excludes rats and 24-gauge ¼- by ¼-inch excludes mice). Woven, galvanized hardware cloth is the strongest compared to welded mesh and most recommended, and hex-head screws appropriate for the substrate (wood, cement, metal, etc.) should be used with washers to fasten.
• For mesh used over ventilator grills, 18-gauge ½-inch mesh, galvanized expanded metal or 16-gauge, ½-inch mesh, galvanized wire cloth is best. The ¼-inch mesh could impede airflow.
• Rubber-encased steel fabric door sweeps are the best for preventing entry of insects and rodents. Mice can still get through high-density brush sweeps by chewing bristles.
• Record and remove pest evidence to document if exclusion techniques are working. Incorporate the cleaning into pricing. Reference www.cdc.gov/rodents/cleaning for ideal cleaning methods.