Except for size, all cockroaches are relatively similar in overall shape and appearance. They are most active at night and stay in the dark whenever possible. (When they are seen in the open or in the light, it usually means that a large infestation is present.) Cockroaches also like to hide in cracks and crevices where their bodies can touch surfaces both above and below. As they grow to adulthood, they will seek hiding places (harborage) for their larger size. Cockroaches do not uniformly infest one room or all rooms. Knowing the basic biology of cockroaches give the pest control technician important clues to the source of a cockroach infestation. By considering the habits discussed below, one can increase the effectiveness of a cockroach management program.

The four most common kinds of cockroaches may be divided into two groups, depending on how they are managed. The "small" cockroaches include the German cockroach and the brown-banded cockroach; the "large" cockroaches are the oriental cockroach and the American cockroach.

  • Management of Small Cockroaches - The German cockroach and the brown-banded cockroach are responsible for most pest complaints and pesticide use in public and commercial buildings. The degree of success of the control program depends not only on insecticides, but on management attention to good maintenance and housekeeping practices. Cockroaches and their egg capsules are being constantly introduced into buildings in packaging and boxes. Consequently, both pest control staff and management must understand that an effective control program must include monitoring and inspection.
  • Management of Large Cockroaches - Although these large insects may wander along pipes throughout a building, in most parts of the county they live mainly at ground level or below. Prevention and treatment should focus on warm, moist areas such as basements, boiler rooms, pipe chases, sumps and elevator or sewer shafts.


Management of Small Cockroaches

The German Cockroach adult is ½ inch long with two black stripes behind its head on the "pronotum" (Appendix I). Young cockroaches (nymphs) are brownish black with a pale brown band down the middle of their back. The German cockroach is not only the most common cause of indoor pest problems, but also represents the largest number of control failures of any structural pest. It is most successful at infesting human structures and withstanding pest control activity. Successful cockroach control programs use several methods to bring the infestation under control.

Behavior and Harborage
Groups of cockroaches (aggregations) live in areas of high humidity and nearby food. They will find harborage (hiding places) into which they can fit closely. As the number of cockroaches increases and favorable harborage is filled, roaches are forced to leave the aggregation or remain in less favorable harborage. They are most active just before dawn and after dark.

To cockroaches, the most desirable harborage is in and around refrigerators, stoves, under sinks, and undisturbed cabinets, which provide both protection and food. Kitchen areas with high humidity, sink traps, leaking faucets, standing water and wet sponges are attractive to cockroaches. They also may be found in washrooms, because of their toilet bowls, sinks, wet wash cloths, and sometimes, water heaters. While there is less food in washrooms, food areas are usually nearby or available through holes around plumbing pipes. These pipes provide additional harborage and areas where cockroaches can enter adjacent rooms.

In schools, German roaches are often found in student lockers or gym lockers. The two principle reasons for this are food left in lockers and roaches transported from home in the student's book bag or coat. In kitchen areas, roaches are most often brought in on supplies. What may be overlooked is that often nonfood supplies are a greater source of roach infestations than food supplies. Vending machines and recycling bins can also provide a frequently overlooked source of roach problems.

German cockroaches are not likely to leave favorable harborage unless conditions change. Such changes can be caused by:

  • increase in the cockroach population,
  • intensive cleaning,
  • reduction of temperature or humidity,
  • mechanical exclusion or
  • pesticide applications.

If cockroaches find new locations with favorable conditions, they can move from one harborage to another, or develop new infestations. Outdoor infestations are found only outside heavily infested structures from which steady cockroach migrations occur and near dumpsters and garbage cans.


Control and Management

With Flashlights - An active inspection with a bright flashlight is the most thorough method of locating cockroaches. The technician can search dark, undisturbed, or remote places of cockroach harborage that have not been properly inspected. Hand mirrors, magnifying hand lens or other small tools may be helpful to some technicians. Identification of harborage is critical to an effective cockroach control program.

With Traps - Use of sticky (glue) traps is a common inspection or monitoring method used for cockroach detection. Correct trap placement depends upon the technician's understanding of cockroach food-seeking (foraging) habits; place sticky traps behind kitchen appliances, in cabinets, supply rooms and similar locations.

Habitat and Harborage Reduction
Speak to the facility staff in a friendly, knowledgeable way. Pest control technicians should explain to both staff and management that often changes in facility operations can reduce or eradicate the insect problem. These recommendations should include how staff can eliminate or restrict materials that support buildup of cockroach populations. Site staff should understand that pesticide application alone will not control cockroaches satisfactorily. Some specific actions that will reduce harborage include:

  • Seal as many cracks and crevices in the kitchen and food storage areas as possible with a good silicone sealer. A review of monthly reports may indicate from time to time that other specific areas may need to be sealed.
  • Repair holes in walls or floors and seal inaccessible areas that could become harborages for pests.
  • Replace wood food storage shelves with wire shelves.
  • Do not store infrequently used items in the same areas as frequently used items and food supplies.
  • Repair all moisture problems.
  • Do not keep recycled goods such as beverage containers, cans, paper, cardboard, etc. near the kitchen or food supply areas.
  • Institute a good cleaning program. Pesticide use without cleaning and sanitation will not produce long term control of a pest infestation.
  • Recommend good lighting.
  • Point out areas that need ventilation.
  • Recommend reduction of clutter (particularly cardboard boxes) and excess product in cabinets or storage.
  • Where practical, install air curtains to keep out flying insects.
  • Recommend rotating stock.

Vacuuming as a Pest Control Method
A relatively new method of "cleaning out" a pest population is vacuuming. This is used to crash (greatly reduce) the cockroach population; it also removes dirt, food particles, etc. The "clean out" is followed by improved sanitation, pest prevention and, if needed, judicious use of pesticides. If vacuuming is used as a pest control method, be sure to use a vacuum cleaner with a HEPA (high efficiency particulate air) filter to avoid suspending materials in the air that can cause respiratory problems.

Pesticide Application
In attacking cockroaches, one should concentrate on monitoring the cockroach population and delivering pesticides into active harborage areas rather than "baseboard spraying."

  • Many types of sticky traps are available to help the technician pinpoint sources of cockroach infestation. Sticky traps are not intended for control, but rather to detect infestations and to evaluate and target control measures. Place sticky traps behind kitchen appliances, in cabinets and supply rooms.
  • Containerized and paste or gel baits should be the standard insecticide treatment for cockroaches in many buildings. The small, plastic bait containers should be placed as close as possible to harborage sites where the cockroaches are actually living. Place the bait stations behind refrigerators, in cabinets and along edges of walls and in corners. Do not place them where students can find them. The two most common mistakes in using containerized baits are (1) not eliminating nearby food sources and (2) not using enough bait stations. Paste and gel baits are most effective when applied in small dabs. Baits are most effective when the cockroach population is low or moderate in size. If there is a large population, the bait in the stations may be entirely eaten before the cockroaches are eliminated. Bait stations should not be contaminated by sprays or dusts that may be repellent.
  • When a moderate to large cockroach population is present, crack and crevice insecticide application is sometimes the most practical and effective way to apply insecticides. Use a narrow diameter extension tube in infested cracks and crevices to provide a thorough application of residual insecticide. (A crack and crevice treatment implies that the stream of insecticide is never visible during the spraying process.) Treat cracks and crevices under furniture, drawers, sinks, around pipes and in high cabinets. First remove utensils and supplies in cabinets; do not treat shelf surfaces.
  • Space treatments should only be used to knock down a heavy cockroach infestation quickly so that other control measures can be used effectively. The need for repeated fogging at short intervals indicates the cockroach population is rising, not decreasing. Space treatments (fogs or aerosol applications) flush cockroaches out of harborage, causing them to cross residual pesticide applications, or the insecticide droplets land on the insects, killing them by direct contact. Such treatments lack crack and crevice penetration. Fog treatments should not be used in areas where facility staff are present. Prior to treatment, all exposed food and food contact surfaces should be effectively protected against pesticide contamination. After the application, food preparation surfaces should be cleaned before they are used for food preparation.

When a cockroach population has been controlled, the technician should continue to monitor the area with sticky traps and interview staff to detect cockroach problems before they become worse.


Brown-banded Cockroach

The Brown-banded Cockroach is less commonly a problem in buildings, but they also can build up large infestations where they find favorable harborage. Adult brown-banded cockroaches are the size of German cockroaches, about ½ inch long. The brown-banded cockroach has two transverse light bands near the head of the insect.

Behavior and Harborage
Brown-banded cockroaches, like German cockroaches, build up the highest populations in kitchens. However, their tendency is to increase in warm rooms. They can be common around high cabinets and areas near stoves and warm motors, such as those in refrigerators, electric clocks, light timers, televisions and radios.


Control and Management

Inspection for the brown-banded cockroach is essentially the same as for German cockroaches. However, brown-banded cockroaches will be more scattered and less attracted to moisture.

Habitat and Harborage Reduction
Habitat and harborage reduction is essentially the same as for the German cockroach.

Pesticide Application

  • Boric acid powders may be used in inaccessible areas. (Boric acid powders should NOT be over-applied so there is a visible residue.)
  • Bait stations with a long active period are effective, but should not be contaminated by sprays or dusts that may be repellent. Place an adequate number in or near harborage. Do not use where students can find them.
  • If baits do not control the cockroaches, use a crack and crevice application to provide a thorough application of residual insecticide: under furniture, drawers, sinks, around pipes and high cabinets. First remove utensils and supplies in cabinets; do not treat shelf surfaces.

The long egg hatching time of the brown-banded cockroach requires treatments to be monitored with sticky traps.


Management of Large Cockroaches

The Oriental Cockroach is often called the "waterbug." Adult oriental cockroaches are very dark-brown or shiny-black. The female is slightly longer than the male, about 1¼ inch to his 1 inch. Unlike other domestic cockroaches, the female does not develop wings, but produces only short triangular wing pads. The male has wings, but they are short and broad, leaving about ¼ of the abdomen exposed.

Behavior and Harborage
Oriental cockroaches favor crawl spaces, spaces between the soil and building foundations, the undersides of stoops and sidewalks, landscaping mulches, water meters, basements and their floor drains and other such moist places. These cockroaches frequently live in floor drains that lead directly outside; these drains are also used as entrances to buildings. The oriental cockroach prefers starchy foods and may build up around garbage cans. They tolerate cooler temperatures, and they are usually found near humid areas.


Control and Management

Search areas of high humidity, such as basements or areas near leaking pipes. Place sticky traps in basements to capture individual insects that may enter from floor drains.

Habitat Alteration

  • Caulk all cracks around pipes and other areas where holes penetrate through ground level walls.
  • Stop water leaks, screen equipment overflow drains and take overflow water away from buildings; keep drain traps full of water or capped.
  • Remove rotting leaves from window wells.
  • Replace mulch around the foundation with plastic porous ground cover and gravel.
  • Move garbage cans away from wet areas.
  • Stop erosion that causes soil voids around foundations.
  • Ventilate moist enclosed spaces.

Pesticide Application

  • Large bait stations or other baits are effective when properly placed in proper quantities. Particular attention must be paid to pesticide degradation due to moisture.
  • If oriental cockroaches are entering from the outdoors, apply insecticides as outside barriers when they can be safely used in areas of known infestation. Use insecticide formulations that are not readily absorbed by porous surfaces (concrete floors, bricks, stones, soil, etc.). Apply them in cracks and crevices.

Numbers observed in the spring may appear low or under control but may build up by midsummer.


American Cockroach

The American Cockroach, like the oriental cockroach, is sometimes called the waterbug. Adult American cockroaches are large (1⅓ to 1½ inches) reddish-brown insects.

Behavior and Harborage
Large populations of American cockroaches live in warm moist habitats. They are most often found in boiler rooms or other harborage with water heaters, floor drains, water sumps and warm moist basements.


Control and Management

Search areas that provide warmth and high humidity. Place sticky traps in areas where American cockroaches may enter a building.

Habitat Alteration

  • Caulk cracks around plumbing and other penetrations in walls, screen equipment drains and floor drains. Keep drain traps full of water or cap them.
  • Remove items stacked in attached garages, entry ways, etc.
  • Replace mulch near doors and window wells with plastic porous ground cover and gravel.
  • Ventilate humid places.

Pesticide Application

  • Many of the methods that control the oriental cockroach will also control the American cockroach.
  • If American cockroaches are entering from the outdoors, apply insecticides as outside barriers when they can be safely used in areas of known infestation. Use insecticide formulations that are not readily absorbed by porous surfaces (concrete floors, bricks, stones, soil, etc.). Apply them in cracks and crevices.

Ongoing monitoring with sticky traps is important due to the long life span of this cockroach.


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