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Jim Criswell
Extension Pesticide Coordinator
Vertebrate animals can damage areas of ornamentals while they are searching for grubs or other soil-infesting insects, seeds, or other plant parts. These animals include:
Control of insects also helps control damage by certain vertebrate animals, because it reduces their food supply.
Skunks
There are two species of skunks in Oklahoma—the striped skunk and the spotted skunk. The striped skunk is the one most often in conflict with man.
Skunks are the least popular of all our wild animals because of the disagreeable scent which they discharge when provoked. Yet, they are very beneficial—stomach analysis have shown that nearly half of their diet is insects, one-fifth mice, and one-fifth fruit. They are particularly destructive of potato beetles, grasshoppers, and white grubs.
The high nuisance value attributed to skunks is caused by their habit of burrowing in flower beds, lawns, and golf courses in search of insect larvae and other insects which constitute a significant portion of their diet. In many instances, these skunk activities are charged to moles or gophers, and the resulting misdirected control efforts are fruitless.
When a skunk raises its tail, it is a warning. Ordinarily, there is no discharge. But, if a skunk believes it is in danger, one discharge will not empty its reservoir. An effective method to neutralize the odor is to wash everything with ammonia water. Netroleum alpha mixed two ounces to a gallon of water can also be sprayed and is effective in clearing the air.
Management
Control is best achieved by removal and relocation, exclusion, or destruction—in that order. Removal and relocation is a desirable measure, since it preserves the inherent value of the animal in a situation where it can continue its part in the environment. To a very limited extent, skunks are considered of value to the fur market when skins are prime. In most cases, wanton destruction is unwarranted and not desirable.
Removal of individuals or families of skunks is best accomplished with live traps. Other traps that kill or maim can result in serious odor problems. Box or live traps should be baited with a chicken head, dead mouse, a portion of canned pet food with a meat or fish base, canned or fresh raw fish, bacon, chicken parts, or whole eggs. Skunks are relatively easytotrap, and, providing the trap is handled with a minimum of jarring or shaking, they can be transported to a remote area and released with little concern for possible musk discharge or someone being bitten by the skunk.
Properly constructed foundations will prevent skunks from digging beneath buildings. In lieu of continuous foundations, screening with quarter-inch hardware cloth is effective for exclusion.
Moles
The eastern mole is the only mole found in Oklahoma. Moles prefer moist soils.
The mole's habits and food are different from those of pocket gophers, as are the methods for their control. Both animals live in the soil, make underground tunnels, and put up earth mounds on the surface.
Moles dig two kinds of tunnels. One is made only an inch or two below the surface of the ground by the mole "swimming" through the loose topsoil. This kind of runway leaves a ridge of earth on the surface of the ground. More permanent tunnels are made six to 10 inches below the surface, and mounds of earth are thrown up at intervals. These are likely to be confused with those made by pocket gophers.
Knowledge of how the mounds of moles and pocket gophers are constructed permits a person to distinguish one from the other. From the main tunnel of the mole run, a short shaft extends straight up to the surface. The soil that is expelled from this vertical shaft wells up like water, and successive loads form a nearly circular mound of which there may be "ripple marks" in the form of complete circles. In contrast, there is a short inclined tunnel to the surface of the main tunnel of the pocket gopher. Through this tunnel, successive loads of soil are pushed out in one direction, each partly on top of the one before, forming a mound of which half circles are visible.
Managing Moles
Moles normally cannot be controlled by the use of poisons because their principal diet consists of insects in the soil and earthworms. For this reason, moles seldom take poisonous baits. When the use of poisons seems to be effective, the user has probably either frightened the mole out of his present runway by the scent, or has killed the food upon which the mole feeds.
If moles are deprived of their food supply, they will be forced to seek another area. Several insecticides are capable of reducing populations of earthworms and soil insects to a point where the soil no longer provides sufficient food to fulfill the mole's daily requirements. The effect on the moles cannot be expected for several weeks, and moles can cause increasing damage as they search in a decreasing food supply.
Trapping is the most universally applicable and satisfactory method of mole control, but it is successful only if the habits and instincts of the mole are carefully considered. Two good traps for catching moles in Oklahoma are the scissor and the harpoon.
To trap moles, select a frequently used runway. Place the traps where the ridge tunnels run in a straight line for a few feet. These tunnels are often used as travel ways. Check the traps at least once or twice each day.
To set a harpoon trap, pack down the runway ridge and push the set trap into the ground with trigger snugly on the depressed ridge. As the mole repairs the tunnel, the trap's trigger will be activated.
Pocket Gophers
Pocket gophers eat the roofs of plants and bring soil to the surface. Besides killing some plants, the dirt mounds are a nuisance.
Pocket gophers build a series of deep runways leading to nests and food storage areas. These generally are about four to five feet below ground. The tunnels are not connected directly to the surface but lead to runways closer to the ground, about 10 inches under the surface.
The amount of soil brought up in the period of a year will vary from one gopher to another and with distances traveled in the search for food. It is estimated in one year the average gopher transports two and a quarter tons of soil to the surface! At this rate, seven gophers to an acre could cover the surface of the ground with a layer of loose soil one inch deep in 10 years.
Management Methods
Control operations can best be conducted during the seasons when pocket gophers are most active near the surface. This usually is indicated by the presence of fresh mounds of soil. Treatment at other times can waste labor and material on unoccupied runways.
The best time to trap gophers is when fresh mounds are found. This is the time pocket gophers are most active in bringing soil up onto the surface of the ground. Traps should be set at fresh workings. Success depends upon proper use of traps. The following steps are suggested:
When using poison grain, use it with extreme care. There are many other animals in an urban landscape which might come into contact with poisoned grain. These are non-target organisms which are very susceptible to the poison. Fumigation is another method of pesticide control. However, fumigants could have limited effectiveness because the gopher burrow systems can be extensive with portions of them blocked off by earth plugs, while the gopher occupies various portions at a time. Fumigants can be used successfully when applied to fresh mounds. Fumigants are not to be used in close proximity to occupied buildings.
Beavers
Beavers have made a tremendous comeback in Oklahoma. These animals are both a curse and blessing, depending on the sites they occur. In many urban landscapes, beavers are not totally welcomed. Beavers will gnaw and fell trees and dam drainages, flooding yards, parks, and other areas.
The only way to manage a beaver problem in urban landscapes is to live trap and relocate the beavers. Trapping and shooting are seldom an option in urban landscapes. Likewise, there are no pesticide products for repelling beavers. To obtain assistance in controlling beavers, contact the Oklahoma Department of Agriculture's Animal Damage Division (405-521-4039) or the Oklahoma Department of Wildlife Conservation (405-521-2739).