Month to Month

— By Dr. Nancy Troyano —

The most common pest issues in restaurants by month — and what you need to know to defeat them.


With plenty of food, sugar-rich beverages, moisture and heat, restaurants are essentially the perfect environment for pests. Battling pests is a daily, year-round war, but it can be hard to prepare if you don’t know what the enemy looks like or from what direction it is coming.

Dr. Nancy Troyano, Rentokil

Based on an analysis of 2 years’ worth of data from restaurants, we were able to determine the most common pests encountered each month in restaurants.

Understanding the most common pests that may be encountered in each month can help op-erators target pest management efforts to ensure that every location is focused on the right concerns in each month.

Knowing the Enemies

Although there are literally hundreds of pests that can become problematic for restaurants, many fall into broader pest categories that behave similarly to one another, so to streamline this data, we grouped pests into 26 categories.

Throughout the year, these are the top 10 pest categories that are the most often serviced in restaurants:

  • Rodents
  • Filth flies (blow, bottle, flesh, house)
  • Small flies (fruit flies, phorid flies, moth flies)
  • Cockroaches
  • Occasional invaders (centipede, clover mite, cricket, earwig, firebrat, ground beetle, millipede, pillbug, silverfish, springtail)
  • Night-flying insects (midges, moths)
  • Spiders
  • Ants
  • Stinging pests (bumble bees, cicada killers, fire ants, honey bee, hornet wasp, paper wasp, scorpions, yellow jackets)
  • Overwintering pests (boxelder bug, ladybird beetle, stink bug, cluster flies)

However, when a monthly breakdown was conducted, clear patterns emerged:

  • Rodents are the most frequently serviced pest in every month.
  • Filth and small flies, as well as cockroaches, are a year-round problem.
  • Occasional invaders also are a year-round problem, although they only appear as a top 5 pest in 8 out of 12 months.
  • Ant issues spike in the spring.

Developing Your Battle Plan

With an outline of the most frequently serviced pests, operators can begin to review their specific locations for potential risks and entry points. Since every location has unique environmental, geographical, structural, vendor and process/product/equipment concerns, no two pest management strategies will be exactly alike — that’s why it’s best to work with a professional pest management provider that can customize a plan based on these factors, as well as a location’s historical pest concerns.

There are universal best practices that can be put into place to reduce the likelihood that pests will be attracted to a facility. Although this is not an exhaustive list, it includes many of the issues and conditions that we see regularly.


  • Close doors when not in use. Remind employees not to prop doors open.
  • Install door sweeps on all exterior doors. Rodent and insect pests can enter through gaps under doors.
  • Do not leave any food or bar fruits sitting out overnight.
  • Clean up food and beverage spills immediately.
  • Seal exterior cracks and crevices that are larger than a quarter-inch, as well as openings around pipes, cables and wires that enter the wall or the foundation.
  • Eliminate clutter to reduce pest hiding places; remove old equipment, excess cardboard or other “junk.”
  • Empty trash to outdoor dumpsters at least daily; all trash should be bagged. Do not leave any trash outside of the dumpster.
  • Ensure that dumpsters have lids that close properly.
  • Trim back exterior vegetation and trees so they do not touch buildings.
  • Keep a 12-inch vegetation-free zone around buildings; keep mulch pulled back from the foundation.
  • Service drain p-traps regularly. Traps that become dry can emit odors that attract pests.



  • Inspect all incoming deliveries for signs of rodent activity; be sure employees that re-ceive product know the process for rejecting deliveries that show signs of a problem.
  • In properties that share walls and ceilings with other businesses, work with your pest management provider to implement extra defensive measures, particularly in the ceiling, where rodents often move between properties.

Filth Flies

  • Work with your pest management provider to implement insect light traps at potential fly entry points.
  • Close drive-thru windows when not in use.
  • If other windows are present in the business and remain open for cooling purposes, ensure that they are screened and that screens are in good condition.

Small Flies

  • Practice ‘First In, First Out’ (FIFO) rotation for produce. Overly ripened, rotting or molding produce is a prime target for small flies.
  • Clean drip trays of soda machines daily to eliminate buildup attractive to fruit flies. Have lines to this equipment flushed regularly.
  • Regularly clean under equipment to remove food and organic debris.
  • Mop floors; avoid power washing or high-pressure hosing, which can push food and other organic debris into cracks/crevices, creating breeding opportunities for small flies.
  • Use commercial floor fans to dry floors after they are mopped, or to dry carpeted areas that become wet.
  • For this same reason, repair damage to floors, tiles and grout as soon as possible.
  • Have a regular floor drain cleaning service performed. Organic slime can build up on the side of drains and create a perfect breeding ground for small flies.


  • Eliminate food debris and standing water that can serve as food sources.
  • Ensure that floor drains and garbage disposals are free of food waste.
  • Develop a process for checking incoming dry goods and foods for cockroach infestation.
  • Ensure that employees have a place to store personal items away from food areas and perform regular inspections and cleaning of this area.
  • Maintain the integrity of wall coverings such as stainless steel or fiberglass reinforced plastic (FRP) to reduce harborage opportunities.
  • Some plants and trees can be attractive to large cockroaches. Work with landscapers or a plant service to select less attractive plants.
  • Utility/boiler rooms can be a target for large cockroaches; be sure these areas are accessible to your pest management provider for service.
  • Clean gutters free of debris so water can flow freely.

Occasional Invaders

  • Maintain tight screening on soffits, weep holes and vents.
  • Caulk all cracks and crevices around window casings.
  • Eliminate standing water.


  • Avoid using natural mulch, such as pinestraw, in ornamental areas adjacent to build-ings. Opt for lava or egg rock if possible.
  • Utilize food storage containers. Food stored in containers is less likely to attract ants through odors.


  • Treat for any insects present. Insects are a food source for spiders.
  • Replace light bulbs with sodium vapor or LEDs to reduce attraction by insects. Where possible, replace lights on buildings with indirect lighting.
  • Eliminate clutter. Spiders like to hide in protected areas.

Night-Flying Insects

  • Close doors when not in use.
  • The best defense against night-flying insects is an insect light trap installed at high-risk entry points.
  • Review exterior lighting, especially in parking lots. Utilize sodium vapor or LED lighting, which is less attractive to insects.

Pest Management is a Partnership

Fighting pests doesn’t have to be single-handed effort. Pest management should be a partnership between a location and its pest management provider.

A pest management provider should give recommendations to help location staff eliminate conditions that are conducive to pest activity. It’s just as important that the location act on those recommendations. If a location is short-handed on staff, its pest management provider may be able to help with some maintenance items.

With this month-by-month knowledge, little elbow grease, a committed pest management ally, and the right plan of attack, the battle against pests is one that any restaurant can win.


— Dr. Nancy Troyano is a Board Certified Entomologist and director of operations, education and training, with Rentokil Steritech, the third-largest pest management provider in North America. Rentokil North America is a division of Rentokil Initial plc. Visit




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