Cockroaches are likely one of the most primitive and hardiest forms of insect life.
THE term cockroach was first mentioned in the English language in 1624, in the ship logs of Captain John Smith, who founded the colony and now state of Virginia in the United States. He referred to this insect as a ‘cacarootch’ from the Spanish-South American word ‘cucaracha’.
Frequently seen aboard ships, Smith commented upon their movements, “creeping into (wooden) chests, which they eat and defile with their ill-scented dung”. What did these sailor’s chests contain?
Regardless of this, cockroaches have been around our planet for a very long time, originating in the Carboniferous period of geological time, some 354 to 295 million years before the present.
Recently scientists at Manchester University in the United Kingdom placed fossils of cockroaches in a computerised tomography (CT) scanner, taking 3,000 X-rays from various angles. They then created 2,000 slices from which they were able to construct 3D images of these fossils.
Early species of these cockroaches may be seen embedded in amber — a yellowish-brownish fossilised resin. It is highly likely that the cockroach is one of the most primitive and hardiest forms of insect life.
Some 4,500 species of cockroach of the order Blattodea have so far been identified. However, it is speculated that a similar number worldwide have yet to recorded.
Only four species are considered as major human pests: the American cockroach (Periplaneta americana); the German cockroach (Blattella germanica); the Asian cockroach (Blattella asahinai) and the Oriental cockroach (Blattella orientalis).
Periplaneta americana is seen at various stages of life.
Very little research has been done on cockroaches — neglected insects by entomologists — apart from the detailed studies of Robert W C Shelford, the erstwhile curator of Sarawak Museum from 1897 to 1904.
In his posthumously published book in 1916, ‘A Naturalist in Borneo,’ he devoted a long chapter (Chapter V) to cockroaches, mantises and stick insects. There he recorded the habits of the Australian cockroach (Periplaneta australasiae) in devouring labels, book covers and anything containing sugar or starch.
Today, the leading authority on cockroaches is George Beccaloni, the curator of cockroaches at the Natural History Museum in London. He has visited Borneo on many occasions.
Most of us associate cockroaches with the word repugnant and sadly politicians worldwide, with a slip of their tongues, refer to opposition parties as cockroaches.
Cockroach races take place in some Latin American countries with heavy bets placed on potential winners. Once we learn about the habits and habitats of cockroaches, we may view them in a different light.
Generally omnivorous, apart from the wood eating species, they are usually found in our kitchens or near our pet food bowls or alongside our garbage bins.
Termites are actually a wood eating form of cockroach. Less than 30 species or just under 1 per cent of the total species of cockroaches are considered to be a threat to human life, for the majority are secretive insects never associating with humans.
A cockroach’s movement within our homes is usually confined to following other cockroach trails in an effort to find a food source. These chemical trails are marked by their faeces. Regrettably, the chemical trails transmit bacteria to our floor and kitchen worktop surfaces.
Whilst they are on the move, they emit airborne pheromones for swarming and mating purposes. Most species are nocturnal in their scuttling movements, apart from Asian cockroaches, which readily fly into a house at night as they are drawn to lights.
For urban dwellers, it is a great consolation to know that the vast majority of cockroaches live in the rainforest with some species burrowing under decayed branches and logs, others on tree trunks and yet more skulking under dead leaves, rocks and even flower-heads.
Cockroaches, as implied earlier, breed by mating and the eggs generated, in some species, grow in the female’s egg case, firmly held within her body. When the egg sack is full, it is partially extruded as the female moves along.
In the case of the German cockroach – common in the urban areas of Malaysia and Singapore – the female emits a long, flat leathery object which is extruded from her abdomen only a few hours before the eggs hatch. The egg capsule or purse contains between 40 and 60 eggs.
The hatchlings take up to four months to reach the adult stage and then may live up to a year or beyond if not detected by humans. In some species, the young are born alive, exiting from the mother to cling to her body in much the same way as baby tarantula spiders behave.
Shelford, whilst near Mount Matang in Sarawak, found a type of cockroach that was able to swim and dive underwater.
How do we cope with cockroaches in Malaysia apart from squashing them in our kitchens – if we are fast enough? Regular mopping of kitchen floors, frequent wiping of kitchen worktops, tightly fitting hoods to garbage bins, placing food in sealed containers, repairing dripping taps and sealing off potential points of entry at the base of walls are all our usual preventative measures.
The simplest and well-tested method of deterring cockroaches is by placing Pandan leaves in cupboards and other areas of the kitchen – the most effective cockroach repellent.
Alternatively, allow a wasp nest to be built in your external kitchen for wasps are very effective cockroach predators even if there is a sting in their tail.
Recently a member of my family, living in a high rise apartment in Singapore, was troubled by an infestation of German cockroaches that had clambered up a garbage chute from five floors below.
The pest control officers sprayed the whole flat with a chemical containing deltamethrin and pyrethrin. It did the trick eventually. Pandan leaves would have been a better preventative, equally effective, longer lasting and much cheaper.
For more enlightenment on cockroaches look no further than ‘A Naturalist in Borneo’ by Robert WC Shelford and edited by Edward Poulton (1916).
For very recent information do read an article by George Beccaloni: ‘Cockroaches: An Amazing Diversity’ at http://blattodea-culture-group.org.