The TerraTrap GS system is primarily designed to trap California Ground Squirrels, but it has also proven effective for catching rats and mice.

California Ground Squirrels are classified as nongame mammals under the California Fish and Game Code. When these animals are causing damage to property, crops, landscaping, or structures, California law allows the property owner or their authorized agent to control them.

Under California Fish and Game Code §4152 and §4181, nongame mammals that are injuring property may be taken at any time and in any lawful manner by the property owner, tenant, or their employees or agents. Pest control companies operate as the property owner’s authorized agent when performing control services.

Because ground squirrels are recognized pest animals that cause property damage, their control falls under pest management and depredation authority, not the regulations governing commercial fur trapping. Laws requiring trapping licenses are primarily written to regulate the commercial trapping of furbearing wildlife for fur harvest, and those regulations are separate from pest control activities.

Mechanical traps designed to humanely kill pest rodents—similar to devices commonly used for rats, gophers, and other pest species—are considered pest control tools. When used for the purpose of protecting property from damaging rodents such as ground squirrels, these devices fall within the legal authority granted to property owners and their agents under California depredation laws.

Live trapping of ground squirrels is regulated differently. The use of live-capture traps for wildlife typically requires a trapping license issued by the California Department of Fish and Wildlife. This is due to the trap types used in wildlife trapping and the requirement that captured animals must be handled and euthanized according to wildlife regulations. This regulatory framework is separate from pest control practices involving mechanical kill traps designed specifically for pest rodents.

The depredation laws referenced above can be found in the California Fish and Game Code, Sections 4152 and 4181, which are available through the California Legislative Information website and other public legal resources.

A dirt bath helps reduce squirrel apprehension. Rubbing dirt from surrounding areas and even directly from burrows onto the trap helps it smell natural and can transfer squirrel pheromones and urine, making the trap feel more comfortable and familiar to them.

With proper setup, squirrels can show activity within a day or two, sometimes even within hours. Most pre-feeding is complete within 3-4 days, allowing the trap to be armed with A18.

The trench is crucial for several reasons:

• It ensures the tunnel is large enough for all squirrels to enter comfortably.
• It allows the squirrel to fall away from the trigger after being dispatched.
• Without a trench, you might experience faster CO2 depletion or even all cartridges being used at once.

Unshelled, unsalted wildlife peanuts are highly recommended, as California Ground Squirrels go mad for them. You should fill the station with lots of peanuts and also place some in the trench near the back of the tunnel. Additionally, throwing 3-4 peanuts down every open burrow within 40-50 feet of the station is advised to attract squirrels to the new food source. While peanuts are preferred, other dry baits like corn can be tested if peanuts aren't working in your specific location.

While the trap can work in open areas, it's generally best to place it near bushes or rocks for cover to make it less visible to the public and predators. Squirrels typically forage 50-75 feet away from their burrows, so placing the trap within this range is effective. Avoid placing the trap directly on a burrow, as this can make squirrels cautious; stay at least 20 feet away if placing it in an open area near a burrow.

This is one of the most common questions we receive — and the honest answer is: it depends on your goals and your squirrel population.

General Rule

A single TerraTrap GS unit can control several acres over the course of a season if it is relocated as control is achieved.

• Stations should be placed within 50 feet of an active burrow system.
• Once activity in that area is reduced or eliminated, the station should be moved to the next active zone.
• In most cases, an acre can be brought under control within 4–6 weeks after the trap is armed, depending on population density.

Population Density Varies

Not all acres are equal.

Ground squirrels typically live in concentrated pockets, not evenly distributed across a property.

• One acre may contain 40 squirrels.
• Another may contain only 10.

This variation directly impacts how quickly control can be achieved.

Speed of Control Matters

The number of stations needed depends largely on how quickly you want results.

Ground squirrel problems usually develop over several years. Likewise, bringing a property back to manageable levels may take more than one season — especially if only one station is used.

• Patient, long-term approach:
  A single unit can make significant progress across 1–5 acres over a season when moved strategically.
• Faster, multi-area control:
  Multiple stations allow you to work several active zones simultaneously.
• Accelerated control in one area:
  Placing two stations in a single acre can dramatically shorten the timeline — often achieving control in just a few weeks.

Larger Properties

For larger properties aiming for meaningful reduction within a couple of years, a practical starting point is:

One unit per five acres, adjusted based on activity levels and expectations.

The overall goal should be to achieve population reduction each year rather than yearly growth. Ground squirrels reproduce relatively slowly compared to other rodents, making long-term population management realistic and achievable when consistent control pressure is applied.  

Scavengers must already be visiting the area regularly. To train them, manually remove the first few caught squirrels and place them 10-15 feet away from the station or in a nearby bush. This allows the squirrel to decompose outside the station and attracts scavengers. Monitor with cameras and try to remove squirrels within 48 hours if no scavenger has taken them, as their scent helps attract other squirrels while giving scavengers time to find them. Once scavengers are routinely removing catches, you can re-evaluate every two weeks.

If there's no activity after a week, consider moving the trap closer to fresh burrow openings. Ensure all pre-baiting and setup steps (dirt bath, trench, proper baiting) have been followed.

The trap should be maintained monthly. This includes refilling the bait, replacing the CO2 cartridge, and relocating it if necessary.