Oriental Cockroaches



Oriental Roaches (Blatta orientalis) are commonly called "water bugs" or "black beetles." They live in damp locations such as basements and around floor drains; they are associated with water. Outside, they live near foundations, crawlspaces, yards, and retaining walls. They feed on filth and decaying matter.

Oriental Cockroach Identification

Oriental roachThe Oriental cockroach is shiny black and is about 1.25 inches long.

They have wings, but the male or female roach can not fly. The total length for the female is 1 ¼" and 1" for the male. The females have small nonfunctional wings while the males have wings that cover about ¾ of the abdomen, nether the female or male can fly. Adults are very dark brown or black.

Picture: University of Nebraska, Department of Entomology

roach comparison image
Cockroaches (left–right): American, Oriental, German and Brown-Banded (Photo by Jim Kalisch, UNL Dept. of Entomology)

Oriental Roach Diet

The Oriental roach eats decayed organic matter in mulch piles and rubbish. This cockroach prefers starchy food and builds up populations around garbage cans.
Most of their water sources come through their food and the moisture around them.

Diseases Oriental Roaches Carry

Since Oriental roaches will eat decayed matter and live in unsanitary conditions, they can carry bacteria over your countertops, plates, and utensils. They can spread e. Coli, salmonella, dysentery, and cause food poisoning.

Habits and Biology of Oriental Cockroaches

Females produce an average of 8 egg Capsules, containing 16 eggs in each, from spring to mid-summer. Unlike other urban cockroaches, the Oriental roach produces only one generation per year, where temperatures are cool. The female will carry the egg capsule(irregularly shaped, black,3/8" long, and 1/4"wide), for around 30 hours and then drops or attaches it in a protected area, near a food supply. The eggs hatch in about 60 days under warm conditions. At least 75% of the eggs must hatch to open the capsule.

The young become adults in 6-12 months. Nymphs(young) are active from about March through much of the summer. During this period, they molt seven to ten times and are reddish-brown to black, except in the first stage, when they are pale tan. The older brown Oriental cockroach nymphs are very difficult to distinguish from the American cockroach nymphs. This type of roach will have a seasonal cycle in its development. Oriental roaches peak to adults during the spring and early summer, dwindling in numbers by the late summer/early fall. Nymphs(young) are active from about March through much of the summer. You only find adult Oriental roaches in early spring. By late spring, nymphs are abundant. As nymphal numbers increase, the adults die off, and by August, any adults are new ones. By fall, almost the entire population is adult.

Habitats of Oriental Roaches

Inside Oriental roaches can be found in damp areas such as basements, crawl spaces, and kitchens, indoors and outside. They tolerate lower temperature ranges than other roaches and may winter in rock walls or such protected sites.

They are commonly found:

  • Under cement foundations; undersides of stoops and sidewalks
  • Stone walls
  • Basements and floor drains and other moist places.
  • Crawl spaces
  • Cracks in foundations; spaces between the soil and building foundations
  • Landscaping mulches
  • Bark mulch under shrubs around the foundation
  • Thick vegetation (especially junipers and ivy)
  • Under piles and debris
  • Garbage and trash dumps
  • Water meters
  • Abandoned cisterns
  • Water valve pits

How Oriental Roaches Enter Your Home

These cockroaches frequently live in floor drains that drain directly outside; they use these drains are also used as entrances to homes. Oriental roaches may enter your house in search of food. During times of drought, there may be a movement towards the inside of the home, but generally speaking, they are found outdoors during the warmer months. They may also move inside if it is unseasonably cold. Oriental roaches often move inside in large numbers, a residual perimeter treatment is recommended for control.

Recommendations for Oriental Roach Control

  • Caulk all penetrations through ground level walls.
  • Stop water leaks, screen equipment overflow drains, and take overflow water away from buildings; keep drain traps full or capped.
  • Remove rotting leaves from window wells.
  • Move garbage cans out of preferred moist habitat.
  • Ventilate moist spaces.

Generally speaking, control measures should concentrate on the outside of the building and points of entry. This control measure is called a "perimeter or barrier" treatment.

Recommended residual sprays for perimeter treatments and basements

Lambdastar Ultracap 9.7

lambdstar ultracap

LambdaStar Ultracap 9.7(Broader label and long-lasting) This residual insecticide may be used inside or outside and will dry invisible. Lambdastar Ultracap has no smell. LambdaStar Ultracap will last longer outside and adhere to the surface better due to its encapsulated technology.

Cyper WSP and Demon WP

cyper wsp

Cyper WSP
Cyper WSP and Demon WP have the same label, but Cyper WSP is more economical.

Demon wp

Demon WP

Demon WP and Cyper WSP will leave a visible residue seen against any dark wood.

D-Fense SC

d-fense sc

D-Fense SC will also dry invisibly with no smell. Use D-Fense SC inside or outside The pint will yield 11-22 gallons.

  • Where to spray these insecticides:
    • You may use three residual sprays: LambdaStar Ultra Cap 9.7, Cyper WSP, or Demon WP inside or outside.
    • Spray outside around doors, windows, pipe openings, and dryer vents. Apply also on the inside on the baseboards near the entry pts.
    • Apply these insecticides on the inside, applying around the plumbing under the sinks and washer and dryer connections.
    • You don't have to spray all the interior baseboards, just the corners, and baseboards inside the garage and basement areas.
  • For additional treatment: You may apply Bifen LP Granules around the base of the house, particularly in pine straw and mulched areas and or Intice Perimeter Bait as supplemental treatments. If you have these larger cockroaches entering inside your home from the attic area (due to trees that overhang the attic or gutters that are not clean) using baits like Intice insect baits, it will give you excellent results.
  • Bifen LP

    Bifen Granulars

    intice perimeter bait

    Intice Perimeter Bait

    Intice Perimeter Bait not only works well around the perimeter, but would also be excellent choices for crawl spaces and or attics.

    LambdaStar UltraCap 9.7, Cyper WSP, and Demon WP, as well as the residual granular, Bifen LP Granules, should be repeated every three months.

    The Intice baits last from 6 months to a year, free from rain. Feel free to call if you have any questions.

    * photograph of the Oriental cockroach is courtesy of: University of Lincoln-Nebraska Dept. of Entomology