Thursday, July 23, 2009


Of all the inconveniences put up by a house wife while doing her daily chores in the kitchen, most persistent one is that caused by the mighty cockroaches. There are about 4000 species of roaches spread all over the world, of which only 30 are associated with human habitats. A large roach can weigh up to 50 gm though majority of them come in the range of 5-10 gm. Smallest one is about 4 mm long while the biggest species can have a wing span of almost 18 cm! They are historical with their ancestors dating back to 350 million years during the carboniferous period. One of the most sturdy living creatures man has encountered, roaches can withstand radiation of the order of 67000 rem, a dose 100 times more than what humans can tolerate. A small dose of 800 rem is supposed to be lethal to human being. German roaches can even tolerate higher doses up to 105000 rem. A decapitated roach can be alive for almost a week reflecting its perseverance and persistence! Which terrestrial creature can hold breath for 40 minutes under water? A roach can!

Since they can live in all climates roaches infest all houses unless preventive measures are taken. Their preference is for tropical humid climates and Indian climate suits them well. No house hold can be immune to the presence of roaches in spite of all preventive measures taken since such measures can only control their population, not eliminate them totally. Generally they live for 3 months and some times for more than 6 months under favorable conditions. They can survive without food for a month as one night's feast is sufficient for living in a hibernated condition. But without water they can only live for a week. They lay their eggs in hard sacs known as ootheca containing several of the eggs, carrying with them for two days before depositing in safe places. A pair of cockroaches can produce more than a lack of descendants in an year reflecting their enormous procreative ability causing population explosion.

Roaches can penetrate crevices of size less than 0.5 mm. Their nocturnal activities are restricted to about 4 hours after the lights are off in the kitchen and 75% of the time they rest hidden from human eyes. They feed on any thing which includes milk, sweets, starchy foods, over ripe fruits, etc. In a normal house hold 50% of the roach population will be in the kitchen as it is the source of food and they know about it. In some houses the roach population can be as high as 1000 at any given time. Left over food materials, food liters on and around the dining tables, unkempt stores, below the kitchen stove where food splattering and spill overs are not cleaned regularly and storage shelves with crevices, attract them for accessing their food needs and for resting and reproduction.

Why do man detests cockroaches? Probably because they are associated with filth. In reality not even a single food poisoning episode in human history has been attributed to this house hold pest though they do carry with them pathogens on their body. One aspect on which roaches are to be viewed with seriousness is their suspected role in inducing Asthma which is thought to be due to secretion of Tropomyosin, a confirmed allergen. Since they do not have the ability to detect foods from a distance, they run over whatever food they come across during their "night out" causing obnoxious smell through their droppings. However there is one place under the sun where roaches are welcome, Texas, USA where farmers discovered their ability to destroy cotton bollworms, considered a pest that affect cotton production in the region.

Boric acid powder, hydramethylnon, deltamethrin, pyrethrin and some pesticides are toxic to roaches. Aerosol sprays containing the pesticide formula with thin delivery tube attached at 45 degree can effectively reach hard to access points to eliminate them. Hydramethynon, belonging to the class of chemicals known as trifluoromethyl aminohydrazone is a metabolic inhibitor highly poisonous to roaches and is extensively used for baiting. Sulfuryl chloride fumigation is effective in controlling their population and periodic fumigation of sewer lines, both inward and outward, is needed to avoid large scale migration into the house. The fact that they cannot travel more than 300 feet makes them create colonies through 'breed and expand' strategy, their travel route being the covered underground sewage lines in the urban areas. Unless and until home owners understand the life style of cock roaches and take precautions to discourage their breeding within their premises, theses uninvited 'guests' are bound to become 'permanent residents', co-existing with the real owners of the house! .


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