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Ball Cockroaches (Perisphaerus sp.), family Blaberidae, Singapore

The Amazing American Cockroach

The American cockroach, also known as the ship cockroach, waterbug, or kakerlac (Periplaneta americana) is one of the most commonly seen species of cockroach, as they have adapted well to live in buildings alongside humans; in the wild they are frequently found under leaf litter, logs, and tree bark or inside active bat caves. They particularly prefer moist, dark environments with readily available food. P. americana is originally from Northern Africa and the middle east, but has since been introduced to every continent.

Waterbugs are some of the largest cockroach species. Adults regularly grow up to 4 cm (1.6 in) long and weigh 1-2 g (0.03-0.07 oz). Both sexes are reddish brown, except for a yellow band around the bottom part of the pronotal shield- a part of their shell that covers the joint between the head and the rest of their body. Both sexes are similar in appearance; males are differentiated from females by their slightly longer wings, which extend past their abdomen.

Kakerlacs spend most of their time in the dark, but they are not necessarily nocturnal; thanks to their large compound eyes, they are extremely sensitive to light. When not hiding from potential predators, they spend their time foraging. American cockroaches have an extremely broad diet; they are known to consume most types of organic matter, including other roaches. This makes them a valuable part of the nutrient cycle, as they're able to break down decaying matter such as rotting wood, fruit, or carcasses. P. americanus is also a popular prey item for many predators including toads and frogs, rodents, lizards, spiders, parasitic wasps, possums, monkeys, and birds.

Outside of mating, American cockroaches do not engage in social behaviors, although they may gather in groups of several thousand when food is plentiful. After mating, the females produce an egg case-- or ootheca-- which contains 14-16 eggs. The ootheca remains attached to her abdomen for two days before being deposited in a safe location. On average, a female may lay up to 10 ootheca in her lifetime. The eggs take 6-8 weeks to hatch, and emerge as nymphs. Over the next 6-12 months, the nymphs undergo 10-13 moults to reach their adult size. A waterbug may live up to two years in the wild, although predation rates for both juveniles and adults are quite high.

Conservation status: The IUCN has not rated the American cockroach. Given its global distribution and affinity for urban environments, the population is extremely stable. In many places, they are exterminated as pests.

Photos

Sheng Li

H. G. Robertson

An Alpine metallic cockroach (Polyzosteria viridissima) near Yarrangobilly, Australia

scene from a wooden handrail in Singapore: