Cockroach Biology and Management

Cockroaches in Alberta have made a serious comeback in recent years. Cockroaches are a health hazard and thrive once introduced where humans live and work, such as in apartment buildings, residential homes, and food establishments. This article will provide a brief overview of the biology of cockroaches and provide some practical tips on controlling cockroach infestations.

Introduction

Cockroaches are serious pests throughout Canada. The German cockroach is the most frequently found species in Canada. They are annoying, and when abundant, they are also destructive. Cockroaches destroy food and damage fabrics, book bindings, and other materials. When they run over food, they leave filth and may also spread disease. They secrete an oily liquid with an offensive and sickening odour that may ruin food. They can also pass this odour on to clean dishes. Cockroach excrement, which they indiscriminately distribute in the form of pellets and looks like specks of brown or black ground pepper, contributes to this nauseating odour and has proven to produce allergies and is a leading cause of childhood asthma.

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cockroach breeding cycle
cockroaches in your home

Biology and Lifecycle

The cockroach has three life stages: the egg, nymph, and adult (see diagram).

Identification From left to right: penny, adult female, adult male, 5th instar, 3rd instar, 1st instar

Cockroach eggs get deposited in groups in a leathery case or capsule called an ootheca. Once formed, this capsule is usually dropped or glued to some surface by the female; however, she carries the capsule, which protrudes from her body, until the eggs are ready to hatch.

There may be from 30 to 48 eggs in the capsule of the German cockroach, but capsules of other cockroaches may have only 10-28 eggs. The newly hatched nymphs have no wings and shed their skins (moult) several times before becoming winged adults. German cockroaches may have several generations or cycles per year.

Where to Look for Cockroaches

Cockroaches hide in dark, sheltered places during the day and come out to feed at night.

They may be found around the kitchen sink or drainboard, in cracks around or underneath cupboards and cabinets or inside them (especially in the upper cor­ners), behind drawers, around pipes or conduits (where they pass along the wall or go through it), behind windows or door frames, behind loose baseboards or moulding strips, on the underside of tables and chairs, in the bathroom, and radio and TV cabinets. (see pictures on cockroach frass and nesting). The German cockroach is usually found in the kitchen and bathroom, although it may be all over the house.

The German cockroach is small, nocturnal, and fast-moving, so it can quickly escape into cracks and crevices in the wall. As such, the German cockroach gets transported through human activities, such as food and equipment dispersal.

Cockroach Frass

dead cockroaches
cockroach management

Effective Control Measures

It would help if you avoided regular spray schedules to reduce the likelihood of insecticide resistance. Instead, leveraging a professional’s integrated pest management approach (IPM) can be used effectively for German cockroach control. We strongly recommend using this holistic approach.

IPM utilizes Inspection and Prevention techniques, directed (rather than broad) insecticide treatments, Sanitation and Exclusion strategies to reduce the use of chemical sprays which may pose a danger to children and pets.

Inspection: Regular monitoring is the kind of early intervention that leads to minimal chemical expo­sure, especially important in sensitive environments and leads to preventative practices, which are crucial to cockroach control.

Good Sanitation & Elimination of Food Sources

Cockroaches do not need large amounts of food to survive, especially in the presence of water. Furthermore, food sources can compete with cockroach baits, decreasing their effectiveness. Elimination of food sources includes:

  • Store and dispose of garbage properly. The highest concentration of cockroaches in a home is usually around the garbage can and the refrigerator.
  • Seal garbage can lids to prevent cockroaches from accessing food sources. Also, keep garbage areas clean by wiping frequently.
  • Dump sink strainers frequently to prevent food build-up.
  • Wash dishes immediately after use. Dishes left unwashed are a significant source of food for a kitchen infestation.
  • Keep kitchen appliances such as toasters, toaster ovens, microwaves, stoves, ovens, and refrigerators free of crumbs and other food debris. In addition, clean the areas around these appliances.
  • Reseal all food after opening or store in the refrigerator.
  • Seal pet food tightly. Do not leave food and water out all the time.
  • Regularly vacuum or sweep under and around furniture where people eat, such as the dining room table. Vacuuming can also remove cockroach egg cases that insecticides will not kill. Remember to promptly dispose of the vacuum cleaner bag in an outdoor container.

Elimination of Water Sources

Water is the most critical factor in cockroach survival. German cockroaches can survive only 12 days with food but no water. However, if only water is present with no food, cockroaches can survive for about 42 days. Eliminate water sources by doing the following:

  • Tighten or patch leaky pipes in kitchen and bathroom areas.
  • Do not let water stand in sinks for long periods.
  • Do not over-water indoor plants because accumulated water will be available to cockroaches.
  • Empty pans under refrigerators used to catch water from condensation.
  • Be aware that pet drinking dishes, aquaria, and pipe condensation (under sinks, in wall voids) can also be sources of moisture.

Exclusion

  • German cockroaches can initially infest a structure when infested grocery bags and packaging get brought inside. Inspect groceries for cockroaches before storing them. Keep grocery bags in outside storage areas.
  • Cockroaches breed prolifically in corrugated cardboard boxes. Discard unnecessary boxes immediately.
  • Dwellings, such as apartments separated by a common wall, are particularly difficult. An infestation can migrate between apartments via the plumbing encased in a common wall. Therefore, cockroaches from one apartment can easily migrate to another, infesting a “clean” dwelling. To help prevent this, caulk holes in common walls and around the plumbing.

Eliminate Harborage

  • In addition to food and moisture, cockroaches require a place to live. The cockroach harbourage is critical to its survival. Cockroaches prefer dark places that are warm and moist. Places that provide tight spaces, such as stacks of newspaper or cardboard, piles of clothing, or cracks and crevices in structures, are ideal.
  • Seal cracks and crevices: Adult cockroaches can fit into cracks only about 1/16 inch and prefer spaces of about 3/8 inch.

Directed Insecticide Treatments

Baits have a high degree of effectiveness against populations of German cockroaches. This bait has the advantage over regular baseboard spray regimes; however, in large infestations, professionals may use trapping and targeted spraying in combination.

Finally, each building and type of infestation are different. An IPM approach should get utilized, which begins with a thorough inspection of the problem and then determining the control strategy based on the complete assessment.

For more information or advice, please call 1-866-ANY-BUGS (1-866-269-2847) today. Our professionals are ready to help you!