STORGARD® WB Probe II® Grain Beetle Trap 

Reduced Trap Length and Efficacy on Beetle Captures 


Three species of beetles, the rice weevil (Sitophilus oryzae), red flour beetle (Tribolium castaneum), and saw-toothed grain beetle (Oryzaephilus surinamensis) are pests of stored grain products such as flour, grain, cereals, rolled oats, beans, nuts, and seeds, among others. 

Rice Weevil Image

Rice Weevil

Rice Weevil, (Sitophilus oryzae)

Red Flour Beetle Image

Red Flour Beetle

Red Flour Beetle, Tribolium castaneum

Saw-Toothed Grain Beetle Image

Saw-Toothed Grain Beetle

Saw Toothed Grain Beetle, Oryzaephilus surinamensis

Infesting stored grain as primary feeders, rice weevil infestations typically start in the field, and in storage, the weevil can easily destroy whole grain kernels. As secondary feeders, saw-toothed grain beetle and red flour beetle feed on broken or damaged grain.


The STORGARD® WB PROBE II® grain beetle monitoring trap will detect most insect pests of stored grain. This specialized plastic probe trap is 13.125-inches long and is inserted horizontally under the grain surface in the center of the bin to monitor for stored grain beetles. This trap functions as a pitfall trap, collecting beetles in a reservoir at the bottom of the trap with minimal labor inputs and increased ease of use to sample beetles over an extended period.


To examine the effect of a reduction in trap length on beetle captures, a comparison study was conducted with the current standard 13.125-inch STORGARD WB PROBE II trap and three shorter trap lengths of 6.5-, 8.5-, and 10.5-inches. This test utilized 7-gallon sealable buckets filled with organic hard red winter wheat to simulate a commercial grain storage bin. Each bucket was filled approximately three inches from the top of each bucket. One hundred beetles of each species were released into the buckets 24 hours prior to the insertion of the probe traps.

Results showed the reduced trap lengths of 6.5-, 8.5- and 10.5-inches caught similar numbers of beetles compared with the standard 13.125-inch length. On average, the 8.5-inch traps caught more beetles overall than all other lengths. Reducing the size of the trap did not decrease the beetle captures. The reduction in trap length still provides optimum efficacy in trap captures, maintaining the WB Probe II traps’ reliability as a useful IPM tool for stored grain insect monitoring.

For further information on the study, please see the Scientific Report WB II Probe Trap: Reduced Length and Efficacy on Trap Catches. For additional information regarding STORGARD® monitoring, please see Stored Product Insects IPM PARTNER® Guidelines for Stored Product Insect Monitoring.

Contributing Author: Charlie Konemann, M.S., Trece Inc 

© 2021, Trécé Inc., Adair, OK USA • ® is a registered trademark and TM is a trademark of Trécé Inc., Adair, OK 74330 USA • TRE-2027