A groundhog burrow system. Graph provided by Purdue Extension Service.

By Jeff Burbrink
Extension Educator Ag & Natural Resources, Purdue Extension LaGrange County

Jeff Burbrink

LAGRANGE — May is a good month to control groundhogs. Also known as woodchucks, these large members of the squirrel family can do a lot of damage to crops with their feeding, as well as undermine the foundations of buildings with their burrowing. I have seen as much as two acres of soybeans decimated around groundhog holes in a field.

The burrows occupied by groundhogs usually have two entrances. One is normally quite visible. The newest burrow next to my barn had fresh dirt thrown out around the entrance this week. The secondary burrow is often not as visible. Often, there is little or no dirt around that entrance. I like to think of that as a secret back entrance tunnel. Groundhogs may also use two or three burrows in a given area over the course of a few days. The one currently living under my barn has two other burrows within 50 yards of the barn.

There is no hunting season or limit on the number of groundhogs you can take. In fields and wooded areas, groundhogs can be removed with traps, by shooting and with fumigation of the burrow. Live traps can be baited with fresh fruit, like slices of apple or orange or grapes. It helps to put a few pieces of bait near the burrow, a few at the trap entrance, and some bait near the back of the trap. Check the trap at least two times a day.

Body gripping traps, sometimes known a Conibear style traps, are a lethal form of trapping. They are placed over the entrance, and baited with similar fruits. This style of trap may be more difficult to set for some people, and requires a special tool to pry the wings of the trap apart, and the trap must be anchored in the soil to be effective.

Fumigants are a cartridge filled with a combustible material that creates lethal smoke when lit. They are typically sold at hardware stores, farm supply stores and a few box stores. Plan on using one gas cartridge per burrow system, and plan to fumigate each known burrow around the area of concern. If there are burrows near your property line, it is wise to team up with the neighbors, because you never know which burrow the little critter might be hiding in. Realistically, you will not get them all on your first fumigation attempt, so plan to purchase 25% more gas cartridges than you have burrows!

Some preparation work must be done in advance to keep the smoke in the burrow, or the gas concentration will not be high enough to kill the pest. I typically use a shovel to level the area around the main entrance. Then, I prepare a piece of cardboard, with some dirt thrown on top, to slide over the hole once the cartridge is lit.

The gas cartridges come with a fuse. These are not bombs, and do not explode, but they do burn intensely, and put out a lot of smoke quickly. There is a tendency for people to light the fuse and throw the cartridge down the hole like a hand grenade! This can result in the fuse separating from the cartridge and not igniting the materials. Instead, install the fuse in the cartridge, and place it gently in the hole. Next, light the fuse, and then slide the dirt covered cardboard over hole. This method keeps you from extinguishing the fuse with dirt being tossed down the hole.

Once the hole is covered, use the shovel to seal any smoke leaks with some of the loose dirt. Look for wisps of smoke coming from the hidden entrance. Plug that hole with extra dirt or a piece of sod. Once you plug the holes, you can move on to the next set of burrows.

Revisit each burrow system in 24 hours. If the groundhog survived fumigation, the burrow will be reopened. Repeat the process until the burrows are not reopened.

It is important to note that these gas cartridges are not for use under buildings. There is often a large gap between the actual burrow entrance and where they go under the structure. And of course, there is the real possibility of setting your building on fire! Traps are a better choice to use traps around structures.

Shooting can quickly eliminate groundhogs where it is permitted. Just remember, bullets, even from a small 22 caliber rifle, can travel at least a mile. Always be aware what is down range. In most cases, a shotgun, which has a limited range compared to a rifle, might be a better choice. Most cities, towns and subdivisions do not allow firearms to be discharged in their boundaries, so trapping is a better option in those settings.