Also see: [About Rats & Mice]

Rat Control

The control of rat infestations is not an easy task. Specific recommendations must be followed before the District will agree to place poison bait stations. Rodents can be trapped or poisoned, but unless rigorous measures are taken to remove food and water sources and nest site availability, the rodents will only return. Additionally, if exclusion measures are not taken first, poisoned rodents will often crawl into wall spaces or attics to die leaving residents with a smelly and messy removal job.

The following measures are recommended before bait or traps are placed:

Rodent Exclusion:

Rats can enter a structure through any hole the size of a quarter or larger. Mice can fit through a hole the size of a dime. When initiating a rodent control program, it is highly recommended that residents exclude all rodents (mice and rats) from structures to prevent future problems. Rodents have very powerful incisors and are capable of chewing through most products. The following sites need to be surveyed and sealed with steel sheeting, steel wire mesh, or steel wool: attic vents, ventilation ports along foundations, basement windows, gaps between roof and chimney, around vent pipes and shafts, and any holes or gaps along roof eaves, between brick and stucco, or under doors. Any opening larger than 1/4 inch must be sealed to prevent rodent access.

Harborage removal:

Harborage refers to locations or resources that are attractive to rodents and which aid in their survival. This includes sources of food and water as well as nesting sites, access routes, and safe hiding locations. Thick vegetation not only provides nesting sites, but also serves to conceal their movements and activities from predators and often provides a source of food. Thick vegetation should be cut back away from structures, thinned out, and trimmed regularly. Dead palm fronds left on trees make ideal harborage and should be trimmed routinely.

Once exclusionary measures have been performed, rodents can be trapped inside of structures if necessary. Appropriate sized snap traps (small for mice, larger for rats) can be baited with peanut butter and oatmeal, fruits, or cat food, and placed along rodent runways. Look for signs of recent rodent activity such as rub marks, rodent droppings, or nests. Check and re-bait traps daily. DO NOT use poison baits inside of structures. Rodents will often travel into inaccessible wall or attic spaces to die leaving residents with a smelly mess.

Rodent Cleanup:

Rodent droppings, nesting sites, and carcasses must be properly removed to ensure your safety. Spray household disinfectant or a 10% bleach solution on any areas frequented by rodents including nests and runways, and on rodent droppings. Wearing rubber gloves, mop or wipe sprayed areas. Do not sweep these areas as this action can cause virus particles to become airborne and increases your risk of acquiring rodent-borne diseases. Dead rodents should be sprayed with disinfectant prior to removal. An inverted plastic bag can then be placed over the rodent, tied, double bagged, and disposed of in the regular trash.

For assistance with rodent problems in the San Gabriel Valley, please call our District at (626) 814-9466. Other areas should contact the local Public Health Department or Vector Control District.