The Surinam Cockroach

With the immanent publication of the Guidebook to Australian Cockroaches, readers of this blog can expect an emphasis on cockroaches for a time. There are additional cockroach photos on the Flickr site noted in the left margin for those who might be interested.

The Surinam Cockroach (Pycnoscelus surinamensis (Linnaeus); Blaberidae; Pycnoscelinae) is one of some 12 known species in the genus. Two have been recorded from Australia: P. surinamensis and P. indica. The latter species has been collected on Norfolk Island along with the former but P. indicus has not been found on the Australian mainland.

In Australia P. surinamensis is known from several localities in New South Wales and Queensland. Despite its name, it is thought to have originated in the Indomalayan Region. Here in Kuranda it is common in compost heaps and in roof gutters where leaves accumulate. It does not seem to enter houses but is of economic concern because it damages plants, especially seedlings, by its feeding habits.

To 1998 it was known as the only obligatory parthenogenetic, thelytokous cockroach. What that means in plain English is that females can reproduce without mating. Males are rare and when the occur they are sexually non-functional.

From an economic standpoint, that means that a single nymph can give rise to an entire population of this cockroach. So the species can be spread easily. The cockroaches are moved about in nursery stock, soil, stock feed and the like. But even though this cockroach is tropical and subtropical its its habitat requirements, it can live quite nicely in greenhouses in temperate regions.

The Surinam Cockroach

Pycnoscelus surinamensis (Linnaeus)

The Surinam Cockroach is easily recognised by its black head and pronotum, the latter of which has a yellow margin near the head. It is a good flier and can be found at lights where it occurs.

Roth (1998) reported that P. surinamensis was derived from its relative P. indicus, a species that has males and is slightly smaller and instead of a black head, has a head with a black vertical stripe. It cannot reproduce parthenogenetically and does not readily, if at all, fly. They live in burrows and are apparently of no economic concern. The distribution of the species is similar to that of P. surinamensis.

Black Butcher-birds, Craticus quoyi, learn to find Surinam Cockroaches all they have to do is toss leaves out of roof gutters-- (but not thoroughly enough to be useful!). The cockroahces are large enough to be worth the effort and are a good source of fat and protein.

The Surninam Cockroach is almost a perfect lab animal. It reproduces readily in captivity and is easily cared for. It does not have a disagreeable odour and females look after their young. Children find them intriguing. 

Literature

Roth, L. M. 1998. The cockroach genus Pycnoscelus Scudder, with a description of Pycnoscelus femapterus, sp. nov. (Balttaria: Blaberidae; Pycnoscelinae). Oriental Insects 32: 93-130.