Oriental cockroach

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Oriental cockroach
a, female; b, male; c, side view of female; d, young.
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Blattodea Family: Blattidae Genus: Blatta Species: B. orientalis
Binomial name
Blatta orientalis Linnaeus, 1758

The Oriental cockroach (Blatta orientalis) is a large species of cockroach, measuring about 1 inch in length at maturity. It is dark brown to black in colour and has a glossy body. The female Oriental cockroach has a somewhat different appearance to the male, appeariing to be wingless at casual glance but has two very short and useless wings just below its head. It has a wider body than the male. The male has long wings, which cover a majority of its body and are brown in colour, and has a more narrow body. Neither the male or female can fly, apparently. The female Oriental cockroach looks somewhat similar to the Florida woods cockroach, and may be mistaken for it.

The oriental cockroach tends to travel somewhat more slowly than other species. They are often called waterbugs since they prefer dark, moist places. They can often be found around decaying organic matter, and in sewers, drains, damp basements, porches, and other damp locations. They can be found outside in bushes, under leaf groundcover, under mulch, and around other damp places outdoors.

In order to thrive cockroaches need a place to hide, they prefer warm places & a relatively high humidity if possible; they also need a source of food/liquid. The optimum temperature for Oriental Cockroaches is between 20 -29 Degrees Centigrade; thus they are rarely found outdoors in the U.K. Female Oriental Cockroaches have vestigial Tegmina (Type of wing cover) and males have longer Tegmina; I have never seen either fly during in over 20 years in the pest control industry! Cockroaches are mainly nocturnal but they are quite happy in large hotels where the lights are on 24hrs a day.

Oriental cockroaches can be elusive in that a casual inspection of an infested dwelling during the day may show no signs of roach activity. I have come across situations where a tenant has complained seeing “dark brown to black colored insects at night”; the landlord goes around checking during the day & thinks the tenant is making it up.

In these cases insect detectors are a very useful tool. Tablets are provided with the sticky trap which contain a "Cockroach Aggregation Pheromone" - Aggregation Pheromones are produced naturally by cockroaches and is a biological characteristic of cockroaches which helps keep them together saving energy etc in not having to go far for a mate.

Other signs of cockroaches are their Oothecae, which are “egg cases” containing up to 16 individual eggs in the case of Oriental Cockroaches. These Oothecae are dropped by females and hatch happy on their own in about two months.

It is one of the reasons why Oriental cockroaches can be harder to get rid compared to other roach species. Adults can be fairly easily killed, by the application of residual insecticide, but of course insecticides can get washed away & two months later there is another batch of fresh roaches hatching out. Roaches also leave fecal marks, which can vary depending on the amount of water supply available. When water is readily available, fecal marks look like lots of little flecks, when water is scarcer Oriental Cockroaches produce fecal pellets similar to mice droppings Adult Oriental cockroaches have quite large fecal pellets which can be mistaken for mice droppings.

It’s difficult to see in the photo but Oriental Cockroaches fecal pellets have lines running along the length of the dropping which is caused by pads in the rectum which are designed to extract water out of the pellet before it is ejected. The arrow shows where one of the lines runs along the length of the roach dropping. Comparison of the three common roaches is below:

Roach	German	Oriental	American
Size(mm)	12-15mm	25-30mm	28-43mm
Habitat	heated buildings - optimum 32 degrees centigrade	20-29 Deg C	same as German
Nymphal development time	6-12 weeks	6-12 months	4 months - 15 months
Life Span	6-9 months	1 .5 years	1.5 years
able to fly?	no	short distance	yes

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