Structural and Public Health Pests: Cockroaches

Pest Management In and Around Structures October 13, 2009 Print Friendly and PDF


Cockroaches most likely to be encountered in schools

Although there are many species of cockroaches found in the US, only a few species are typically problems in schools. Cockroaches are often referred to by common names including waterbugs, palmetto bugs, etc.

Effective management includes cultural and mechanical practices such as removing incoming products from cardboard containers as soon as they are delivered, cleaning drains regularly, removing other water sources such as leaking pipes and faucets, and sealing cracks and crevices in food storage, preparation and serving areas including openings around the edges of electrical boxes, bulletin boards and signage. Due to the development of effective insecticide bait formulations, cockroach problems have become much less prevalent in general. Spray-applied liquid insecticides are much less effective than baits in reducing cockroach populations and increase potential for exposure.

Table 1 Cockroaches most likely to be encountered in schools.

Common name Geographic distribution
American cockroach Throughout the U.S.
Brownbanded cockroach Throughout the U.S.
German cockroach Throughout the U.S.
Oriental cockroach Throughout much of the U.S.
Smokybrown cockroach Throughout the southern U.S.

Monitoring and inspection for cockroaches

The number one monitoring tool for cockroaches is an adhesive-coated, cardboard insect monitoring trap. These inexpensive devices should be placed in vulnerable areas including food storerooms and preparation areas, and anywhere else cockroaches have been a problem including laundry rooms, custodial closets, staff lounges and student stores. Insect monitors are exceptional in detecting cockroaches but also in indicating direction of travel, species present and whether immatures as well as adults are present.

These adhesive-coated cardboard traps are purchased pre-coated. For cockroaches, the ideal designs fold or are purchased pre-formed such that the sticky surface is enclosed within a cardboard \tent. to protect the adhesive from dust and debris. Food service and other staff must be alerted to their presence so that they do not disturb or remove them when cleaning. Some devices include a pheromone attractant although this enhancement is not required for effective monitoring.

Ideally, each device should be dated and numbered, and its location noted on a map or diagram of the facility or vulnerable areas. Wall tags, e.g., a colored sticker placed at eye level on the wall above the device and numbered # of #, e.g., 1 of 6 total devices in the room, can help the technician relocate these quickly during inspections. The device should be placed on the floor or under-sink cabinet floor, and up against the wall, with the entry/exits to the monitor parallel to the wall.

There is debate among professionals as to whether glue boards should be located in every potentially vulnerable area, e.g., under sinks in classrooms, or just in kitchens and food storerooms, or even used at all in facilities that have never experienced a cockroach problem. Checking these devices takes time and if no captures are recorded over an extended period, perhaps that time is better spent on other priorities

A good strategy may be to use these devices when the IPM program is initiated, and re-evaluate use after six months or more. Old, dust-covered, undated cockroach monitoring traps are frequently found during a walk-through of schools and other facilities, and are a sign that good intentions do not always coincide with practical realities. It may be preferable to limit the number of devices used to vulnerable areas where complaints have occurred in the relatively recent past than to load up a facility with traps that cannot possibly be maintained properly due to time constraints and proper prioritization of activity by IPM professionals. On the other hand, these traps will capture a wide variety of pests including mice and the occasional cricket, scorpion, spider, ground beetle, stored product pest or other invader, and can alert those checking the traps to incipient problems well before they might otherwise be noted.

In some locations, public health inspectors have recorded violations when insects are found in these traps during their inspection. If that is an issue, food service staff can be trained to inspect the traps daily, discard any with captures and report the capture to a central office and/or record the capture information directly in a pest sighting log housed at the site.

Cockroaches are primarily nocturnal – active at night and in harborages during the day. They are thigmotactic, preferring to harbor in locations where they have surface contact on both upper and lower body surfaces, hence their liking for the flaps of cardboard boxes and the space between wall-mounted fixtures and the wall. These are key locations for visual observation for cockroaches, egg cases and feces.

Inspection practices should include checking for unsealed openings such as missing or loose pipe and conduit escutcheons, unsealed edges around sinks and cabinets, unsealed edges of bulletin boards or wall-mounted electrical panels, mirrors, light fixtures, fire alarms or emergency lighting. Inspections should focus on areas where food and water are present including food storages, kitchens, food serving lines, cafeterias, locker rooms and staff lounges.

Cultural and physical strategies for cockroaches.

  • Remove individual cockroaches using a vacuum or wipe.
  • Use a flushing agent, such as compressed air, directed into cracks and crevices harboring cockroaches and vacuum up cockroaches as they emerge.
  • Eliminate the harborage by sealing cracks, sealing edges around wall-mounted electrical panels, light fixtures, bulletin board, posters, etc.
  • Clean up food and drink spills immediately.
  • Remove food products and food service supplies from cardboard containers as soon as they are delivered and put cardboard in outdoor recycling containers to avoid introducing cockroaches and egg cases.
  • Inspect incoming products for cockroaches, droppings or egg cases and discard infested products.
  • Follow up with suppliers who deliver infested products and change suppliers if the problem is not resolved.
  • Store food items in sealed containers.
  • Use liners for waste containers and empty at the end of the day so that food and food waste is not left in the building overnight.
  • Place exterior trash cans and dumpsters away from building entrances.
  • Fix plumbing leaks, gutters that hold water and damp wood to eliminate access to water.
  • Position exterior lighting to avoid attracting cockroaches to building entryways at night.
  • Use sodium vapor or yellow bulbs for exterior lighting to reduce attraction to cockroaches.

Table 2 Commonly used products for physical, cultural or mechanical management of cockroaches and uses.

Type Example Products Uses
compressed air, aerosol can many flush cockroaches from cracks, crevices and other harborage.
insect monitors Catchmaster® Trapper® Monitor and Insect Trap Victor® PCO Roach Pheromone Trap monitoring device indicates presence, species, relative numbers, direction of travel, location of harborages; use can suppress populations
sealants many seal cracks, crevices including edges of wall- mounted equipment to eliminate harborage
vacuum, HEPA filtered Sierra Backpack Vacuum vacuum up cockroaches, ootheca, droppings and associated debris

Pesticide options for cockroach management

Chemical management options that reduce potential for exposure include insecticide baits in pre-manufactured, enclosed bait stations, or gel or liquid baits placed in cracks and crevices.

Chemical options that increase potential for exposure for students, staff and other facility users include spray formulations applied to exposed surfaces. These formulations are typically much less effective than baits for cockroaches.

Chemical options, including baits, should not be used on a routine or calendar-based schedule but only where cockroach presence has been confirmed and non-chemical measures are also implemented.

Priorities for cockroaches

  • Additional research.
  • Efficacy of botanical pesticide products for cockroaches including residual activity.
  • Strategies for deployment of insect monitors, i.e., how many, where and when to place or remove monitors.
  • Education connection between cockroach infestations and asthma in children.
  • Heath department education on benefits of insect monitors for cockroaches and detrimental effect of considering trap captures to be health code violations.

Additional resources for cockroach management

Arizona Cooperative Extension. 2005. Cockroaches. Pest Press. (PDF)
Daar, S., T. Drlik, H. Olkowski and W. Olkowski. 1997. Chapter 6. IPM for cockroaches in schools. Pp. 35-48. In IPM for Schools: A How-to Manual. Line drawings, identification, communication, monitoring, management.
Ogg, B., D. Ferraro and C. Ogg. 1996. Cockroach Control Manual. University of Nebraska Cooperative Extension. Color images of adults and egg cases, identification, biology, least-risk management, public health.
Rust, M.K., D.A. Reierson and A.J. Slater. Undated. Cockroaches. In How to Manage Pests of Homes, Structures, People, and Pets. University of California.
University of Florida. Least Toxic Methods of Cockroach Control. Undated. In National School IPM Information Source.

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.