It’s been three months since we last installed new subterranean termite monitoring blocks at Site 1 in San Jose. You’ll be surprised by the difference 90 days make.


Thrasher Termite & Pest Control is partnering  with University of California Cooperative Extension in a research study to evaluate subterranean termite bait systems over a two-year period. With the support of the homeowners, we selected three residential houses as  research sites. At each site we installed pairs of plastic below-grade stations around the perimeter of the house. One station in each pair contains a professional-grade subterranean termite bait, the other station contains non-toxic wood blocks for monitoring purposes. The monitoring stations are checked every three months to evaluate subterranean termite activity and to collect subterranean termite samples for DNA testing. The tests will help us determine the number of distinct subterranean termite colonies around each house.

Subterranean termite bait station with non-toxic monitoring block.

Subterranean termite bait station with non-toxic monitoring block installed next to a station containing active ingredients.

180-Days Since Installation:

At 180-days since the original  installation and 90-days since the last time new monitoring blocks were installed, we are seeing a lot of activity at Site 1. This 75-year old 2,000 square foot home has an abundance of old wood in the landscape: tree stumps, wood fences, wood-chip mulch. Our goal is to keep the subterranean termites in the landscape from feasting on this house. Of the 14 monitoring stations around this home, 7 had termite damage, and 5 of those had extensive live subterranean termite activity.

Site 2 (1800 square foot, single-level residential home, stucco walls): Two monitoring blocks with termite damage; no live termites.

Site 3 (3000 square foot, two-story residential home with wood siding): Several  monitoring blocks with termite damage; two blocks with live termites.

In Northern California, Western subterranean termites are most active January through June while the upper level of soil is still moist and cool. In the summer and fall subterranean termites retreat deeper underground, but may still be found at surface level in irrigated yards.

Subterranean Termite Monitoring Blocks after 3 months

All six of these subterranean termite monitoring blocks were installed three months prior. Some, such as those in the top row, showed little termite activity. Others, such as those in the bottom row show extensive damage from subterranean termites.


Different feeding activities of Subterranean Termites

These blocks illustrate the different feeding activities of subterranean termites. On the left, termites mostly began feeding at the end grain of the wood and “drilled” down through the block. On the right, the pale area of wood shows where subterranean termites stripped off the surface area of the block.


wood block with subterranean termite galleries running the depth of the wood

Another wood block with subterranean termite galleries running the depth of the wood. The discoloration is staining from mud and fungus. Notice the subterranean termite photo-bombing this image!


Subterranean termites fed on the outside and inside of this wood block

Subterranean termites fed on the outside and inside of this wood block. When we extracted the block from the underground station, hundreds of subterranean termites poured out.

Research During a Pandemic:

Our UCCE researchers were granted permission to continue this on-going, multi-year study during the pandemic. Following current state-wide safety protocol, both researchers wore face coverings and gloves, and maintained a six foot separation between each other and the public. The field research is conducted out of doors, providing an additional level of safety to the researchers.

Subterranean termite bait system study lead researcher Andrew Sutherland, Ph.D, BCE, SF Bay Area IPM Advisor, UCCE

Subterranean termite bait system study team member Casey Hubble-Wirgler, Staff Research Associate, UCCE

Next Steps:

We’ll be getting the termite colony DNA results soon. This data will let us know how many distinct subterranean termite colonies are at each of our research sites. In three months we’ll be checking the monitoring blocks again AND opening the bait stations for the first time in six months. The more bait we see consumed, the lower the count of live termites we expect to encounter.


Previous research showed that a typical residential lot often contains multiple unrelated colonies, each attacking the home from different locations. One common treatment method is a liquid perimeter treatment of the home with a pesticide formulated to kill termites. Baiting provides a different, more targeted approach to termite control.

The professional-grade subterranean termite bait systems being studied are all proven to work. This study looks at different aspects of the systems including the success of baiting at the time of installation, the time it takes for Western subterranean termites to find the bait, the number of distinct colonies in a location, and the speed of colony control. This study is being conducted by UC Cooperative Extension with several pest control partner companies. It is funded by California’s Structural Pest Control Board. Thrasher is participating in an evaluation of the Ensystex subterranean termite bait system.

Three San Jose property owners volunteered their homes as field sites for Thrasher Termite & Pest Control and UC Cooperative Extension. Subterranean termites were found within four feet of each of these homes, putting them at risk for infestation and damage. Subterranean termite bait systems were installed around each of the homes and will be monitored for the next two years. For purposes of confidentiality we can’t name these volunteers, but we truly appreciate their willingness to advance the science of termite baiting.