Recommendations for preventing pest contamination of pallets and containers 

Did you know that ISPM 15 compliant wood pallets, as well as exempt pallets made from other materials, may still be at risk of contamination by invasive species known as “hitchhikers?” These basic steps can help.

Brown marmorated stink bug

A hitchhiker pest, the brown marmorated stink bug is native to China, Japan, the Korean Peninsula, and Taiwan. It was first found in North America in 1998. Source: Wikimedia Commons

The movement of any commodity or conveyance bears some risk of transporting invasive species through either infestation or contamination. In order to best mitigate these risks, there are regulations that are designed to combat potential infestation (such as ISPM15, designed to practically eliminate the risk of moving wood-borne pests that can be present in solid wood packaging) as well as regulations and best management practices that could be applied to nearly any situation where pest contamination may occur. 

Once properly applied, the ISPM15 treatment should minimize the infestation risk profile of any given piece of solid wood packaging, as the unique pest infestations that can occur within solid wood should have been eliminated. At this point, treated solid wood is functionally the same as engineered wood from the pest perspective, while non-permeable surfaces such as plastic or metal would have different – and likely neither better nor worse- risks associate with them. Regardless of material, all conveyances can be pathways for a different class of pest- known informally as “hitchhikers”- which can include; adult organisms sheltering anywhere in or on a conveyance, pests that contaminate the conveyance through laying their eggs on solid surfaces, and water or soil-borne organisms.

Recommendations to prevent common types of pest contamination of any conveyance- including solid wood pallets, plastic pallets, crates, dunnage, metal containers, and more- would be to store these items:

  • Indoor whenever feasible– when it is possible to store conveyances indoors in a dry and clean area, this is a very simple and effective way to minimize potential contamination by many invasive pests.
  • As far away from live trees as is practical– this will lessen the chance of contamination from insects that lay eggs on solid surfaces, like spotted lanternfly and European gypsy moth.
  • Not under bright lights, especially at night– many insects, especially moths, are attracted to bright industrial lights and may then seek shelter or lay eggs on any objects near the lit areas.
  • Off the ground, ideally atop a dry riser and/or on a solid surface (such as a concrete floor)- this will lessen the chance of soil, mud, or waterborne species splashing, soaking, or tunneling into the conveyance, thereby contaminating it- this may apply to pests like nematodes, imported fire ants, terrestrial snails, and other soil and water-based invasive species. 
  • Not in grassy or weedy open yard areas– this lessens the chance that invasive species such as insects and snails found in the plants will lay their eggs or seek shelter within the conveyance’s structure or surfaces.

Know your local pest situation and consider how to best to protect your business– different places have different pest threats that will apply to their area. Some problems, like the spotted lanternfly, are only in a very specific area at this time. Others, like the brown marmorated stink bug, are found in almost all 50 states and in four Canadian provinces. In the USA, it might be wise to speak with your State Plant Health Director (SPHD) to learn what local invasive species concerns apply to the storage of pallets. Find your SPHD here: . In Canada, the Forestry branch of your Provincial Natural Resources department is your preferred point of contact.

Once you understand your local pest situation, take steps during peak risk seasons if identified– some pests have specific risks associated with the seasons, such as when the pest is prone to flying long distances, or when they lay eggs. Learning these specific peak risk seasons can help you protect your business most effectively. This information should be available from your State Plant Health Director or Provincial Natural Resource officer.

All trade activities contain some risk for the accidental movement of invasive species. By combining the treatment requirements of ISPM15 with the best management practices outlined above, the pallet industry can further minimize the risk of their product bearing both infesting and contaminating pest types.

Written by Leigh Greenwood, The Nature Conservancy, with assistance from Brad Gething, NWPCA and Scott Geffros, CWPCA