by Courtney Llewellyn
Local and national news often report worrying cases of foodborne illnesses, and according to Matt Frye with the New York State IPM Program at Cornell, an unknown number of food contamination cases relate to pests. The pests, usually rodents and birds, can contaminate produce with their feces, urine, hair, body parts – and even whole carcasses.
The important points to consider when it comes to pest management are setting thresholds (what amount, if any, of pest problems are you willing to tolerate), then addressing why your controls aren’t working. Next, identify all your pests, and finally, eliminate those pests.
Rats! (And Mice)
“Rodents are destructive,” Frye bluntly stated. “They cause up to 25% of fires by chewing on wires. They cause landscape damage, product contamination and product destruction, affecting your brand and public health.”
He added that rodents can carry human pathogens, noting that Salmonella is viable in rodent droppings for up to 86 days. Rodent droppings can affect humans through both ingestion and inhalation.
The three most common nuisances include the house mouse (which always lives near food and a heat source, and can live its entire life indoors); the field mouse (which lives outdoors, but can come inside to nest in the winter); and the rat (which burrows outdoors, but has been known to nest inside for the winter). They will all come inside your storage or packing facility if food is easily accessible.
How do you keep them out? Frye said there are generally three lines of defense: at the fence line, bait stations are placed 50 – 100 feet apart; at the edge of building, bait stations are placed 20 – 40 feet apart; and passive stations (with no bait) are placed inside the building. “There is no research supporting these intervals of spacing, though,” he said. “It’s just the practice that’s been done.”
Rodent biology means they tend to follow lines and explore dark spaces, so placement ties directly into how effective a device will be in trapping them. Rodents can experience “station fatigue,” though – if they become used to a bait station they begin to ignore it.
Frye suggested increasing trapping efforts on the south and west sides of buildings, as in studies they routinely saw more regular feeding (because they tend to stay warmer). He also recommended removing excess vegetation, old equipment and other possible pest shelters outside.
“The biggest thing to do is to limit access by sealing holes, closing doors, et cetera,” Frye said. “Focus on edges and corners and shadowy spaces inside.”
Beware the Birds
Birds can also carry human pathogens. Like rodents, they consume and damage produce and contaminate with their feces. Their nesting can become an issue as it can damage fixtures and lead to fire hazards. Nests can clog gutters, leading to water damage.
Unfortunately, federal, state and local agencies all have management rules for migratory birds, which makes getting rid of nuisance birds an issue – with the exceptions of pigeons, English sparrows and starlings. Everything else may require specialist exterminators or special licenses.
As with rodents, habitat modification is necessary to reduce roosting and nesting, as is sealing access. There are several different options to keep birds away as well:
- Netting: This can last five to 10 years and works fairly well; check your fire code before installing
- Spikes: Often made of plastic or metal, these discourage roosting or nesting on ledges; they cost a little more, but are easy to install
- Post and wire system: These protect ledges and flat surfaces and are cheap and easy to install
- Electrified systems: These utilize a tape-like material with wires that send minor electric shocks to birds; they’re not dangerous to humans but do require regular maintenance; they come with a low fire risk
- Suspended plastic strips: A very easy solution to cover doors to prevent entry
- Fear-provoking stimuli: There are several options here, such as reflective materials, balloons and “giant eyes.” They require effort to delay habituation. They work best when they include some movement, if you install, uninstall and then reinstall them, or if you reinforce them with activity (a wolf cutout and an actual dog)
- Repellents: There are many options on the market (in gels, pastes, etc.), but data so far show consistent repellency is lacking
“Your goal is a pest-free environment,” Frye said. Because pests cause systemic problems, from the grower to the distributor to the retailer to the consumer, avoiding them is very important. Doing so relies on early detection and a rapid, planned response. For more information, Frye recommends reading “Beasts Begone!” at tinyurl.com/uto546c.