Pocket gophers are burrowing rodents (of the Geomyidae family) named for the fur-lined pouches or pockets on the outside of their cheeks that they use to carry nesting materials and food. They move about in underground tunnels and hoard food in subterranean chambers. Garden vegetables are among their favorite foods.
Pocket gophers are from 6 to 10 inches long with small eyes and ears, short fur and powerful front legs with large digging claws. They leave holes on the surface of the ground, usually plugged, located next to horseshoe or crescent-shaped mounds. Moles, another burrowing rodent, leave round, volcano-shaped mounds. Moles leave a raised ridge as they burrow just beneath the surface.
Pocket gophers dig burrows 2 ½ to 3 ½ inches wide that are 6 to 12 inches below the surface. They create short, sloping lateral tunnels from the main burrow to the surface; they store food in chambers as much as 6 feet deep. Their burrows can cover 200 to 2,000 square feet.
Pocket gophers don't hibernate; they are active all day, every day year-round--although you might not see fresh mounds. They smell their food, including roots; they sometimes dig moundless "feed holes" to the surface to eat vegetables and other plants. They can yank entire plants down these holes.
To trap gophers, you have to find their main burrow. Probe the ground with a metal rod about 8 to 12 inches from the plug side of the mound. The rod should have an enlarged tip; you can make one or buy a commercial model. The rod will suddenly drop about 2 inches when you've found main burrow, usually from 6 to 12 inches deep.
The most common gopher trap has a two-pronged pincher that snaps shut against a flat, vertical pan. Choker-style box traps also work; they require more digging, but they are especially good in tunnels smaller than 3 inches wide.
Set traps in pairs in opposite directions in main burrows to trap gophers coming and going. It's not necessary to bait a trap, although you can use peanut butter, fruit or vegetables as bait. Wire your traps to stakes so you can retrieve them easily.
To keep gophers out of your vegetables bury a ¾-inch galvanized poultry wire at least 2 ½ feet deep around your garden. Bend the last 6 inches at a 90-degree angle away from your vegetables. This wire can block tree roots, and determined gophers can sometimes dig under it.
Poison and Fumigation
Grain treated with strychnine and baits containing 2 percent zinc phosphides are available to kill gophers. An anticoagulant bait, which causes gophers to bleed to death internally, are best if there are no children around. However, 10 times more anticoagulant bait than strychnine is needed--and it has to be applied multiple times.
Use a spoon and funnel to place toxic bait in several locations around the main tunnel, not a lateral tunnel. After you've placed the bait, tamp down the hole that you made. Always follow label instructions.
A pest control professional can fumigate gopher tunnels with aluminum phosphide. For small tunnel systems hook a vacuum cleaner hose to the exhaust of an automobile and funnel carbon monoxide down their hole.
Commercially available devices use a mixture of propane and oxygen to set off explosions in gopher burrows, killing them by concussions. These are dangerous to use; they can damage your garden and are too loud for residential areas.