Knowledge Base

Baiting rodents with rodenticides is another effective means of control. Often, baiting is the most efficient and timely way to eliminate large numbers of rodents. The main disadvantage is that rodenticides are toxicants and must be used carefully to avoid harming people, pets and other non-target animals. As with all pesticides, precautions (and associated risks) must be taken when using rodenticides. All rodenticide product labels emphasize that baits must be secured in tamper-resistant stations or placed in areas (crawlspaces, attics, sewers) inaccessible to children and non-target animals.

Tamper-resistant bait stations are designed to prevent children and non-target animals from accessing bait. They are usually made of hard plastic or metal. They must be lockable and secured to the ground, a fence or a structure. Cable ties can be used, especially for attachment to fence lines. Stations also can be fastened to the ground with stakes, or attached to patio blocks by bolting or gluing. The use of patio blocks is advantageous in elevating stations above ground level moisture problems. The stations also must lock, usually by built-in lock and key mechanisms, and the bait blocks inside should be secured with wire or skewered on metal rods designed for that purpose.

Bait stations should be numbered and labeled, and their locations mapped. A label on each station should warn of the rodenticide within, and include the user’s name and contact information. The station should also have a card or label on which technicians can record the date each station is checked.

Around larger commercial facilities experiencing significant rodent activity, bait stations are often placed 75-feet apart around fence lines, spaced at 50-foot intervals against the building’s exterior, and indoors at 25-foot intervals along exterior walls. Such spacing can be made smaller or larger, to match the level of rodent activity. If bait is consistently being taken only along one corner of a structure, it may be beneficial to move bait stations from other areas to that corner, or simply to add more stations to the area experiencing the greatest rodent activity.

In addition to using bait in bait stations, bait can be placed directly into rodent burrows. The bait should be placed deeply enough to be considered inaccessible to humans and non-target animals. Burrows, especially those of rats, can be checked for activity by stuffing newspaper, leaves, etc., into the openings, then checking 24 hours later to see if rodents have reopened the burrows. If activity is noted, a cup of bait pellets (not block bait or place packs, due to their greater potential for being kicked out of the burrow) can be inserted deep into the burrow. A few days later, the burrow can again be checked for activity to see if the rodents were eliminated.

Rodenticides come in a variety of forms and formulations. Bait blocks are preferred for use in bait stations. Grain, pellet baits and pellets in place packs can be shaken out of stations and trans located (carried away) by rodents, creating a potential for poisoning non-target animals. Liquid baits are also available. These can be used effectively where rodents (especially rats) have ample food resources but limited access to water. Like solid baits, liquid baits should be housed in tamper-resistant containers or be placed in areas inaccessible to children and non-target organisms.

Selection of which bait product to use is also specific to the situation. Considerations include rodent acceptance of and resistance to the rodenticide, the amount necessary to kill a rodent (single or multiple feedings), the bait’s toxicity and secondary poisoning potential, and the potential for contaminating food and poisoning non-target organisms including humans.