PicoBlog

In the last week we had some discussion (again) about red-headed roaches on the SAPCA WhatsApp group. What follows is my experience with the species. Red headed cockroaches (Deropeltis erythrocephala) are a large species with adults reaching 60mm in males (including wings) and 50mm in females (Fig. 1). Females are apterous (no wings) and males have fully developed wings and are capable of flight. The red colouration is present in the legs and the head, but antennae are long and black (Fig. 2). The species name, erythrocephala is derived from cephalon – meaning head, and erythraeous – meaning red colour (Nicholls, 1989). The oothecae (egg case) are large (20mm), black and have a hardened exterior (Fig. 3). Females do not carry but often deposit the ootheca in moist areas. This species is slow moving and often found outdoors near water or damp spots – under pot plants is a common harbourage for them. Although this species has been predominantly an outdoor species, there have been an increased number of reports of them clustering inside the household, particularly the ceilings and roof areas (see photo of typical cluster in a roof below). It is unclear at this stage why this species is now choosing to inhabit domestic structures, and why there are more and more complaints about their presence (in the Western Cape at least).  They do not seem to move into kitchens and similar areas where food is abundant. Current findings show they do consume a diet of fresh food, including protein.

We have managed to colonise this species in the breeding room. They are fed a diet of dog biscuits and fruit in the lab colony.

From what is currently known about their control, residual sprays with Rossi 200 Super (fipronil + lambda-cyhalothrin) are effective in controlling them. Other residual sprays would probably also be effective. I have also tried to check whether the species will feed on gel baits like other cockroach species. The photo shows a test group and a control group of 5 males and 5 females. The bait we tested was Advion Cockroach Gel (indoxacarb). The photos below show the control group (bottom), still fine after 3 days, and the test group, all dead or dying after 3 days. The container had shelter, water, and normal diet (dog biscuits) available. The test group additionally had 0,2 g of Advion placed on a microscope slide in the container. We did not replicate the experiment.

When handling them they will often extrude a defensive secretion from the femur/tibia joint on the back leg, which stains the skin a brown colour.

If you go to most larger pet shops around South Africa you will also be able to find a cockroach for sale called dubia roaches. This species is bred as food for reptiles etc. What I don’t understand is how these roaches have been allowed to enter the country (actually be brought into the country) for breeding purposes. It is an exotic animal, and although it probably won’t invade houses, escaped specimens could establish themselves in an area like Durban where the climate may be suitable.

A literature search of Web of Science (using the scientific name only as search term) identified only one scientific paper related to this species (Leonid, 2014), which contains a redescription of the species, so very little other information is available on the species’ biology.

There is another species of redheaded cockroach, Oxyhaloa duesta, which is often sold as a pet (yes, some people keep roaches as pets, especially the Madagascan hissing roach) or for breeding for feeding pet reptiles and snakes etc. This species is not known infest houses. It is also a South African species, and may be confused with the red-headed cockroach.

References

LEONID, N. A. 2014. New and little known Blattidae (Dictyoptera) from the collection of the Museum d'histoire naturelle de Geneve. Revue suisse de zoologie., 121, 33-50.

NICHOLLS, S. W. 1989. The Torro-Bueno Glossary of Entomology, New York, The New York Entomological Society.

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