Fooling clothe-eating male moths to remain bachelors

Abraham Lincoln, over 200 years ago, said: “You can fool all the people some of the time, and some of the people all the time, but you cannot fool all the people all the time.” This is what the Khongsai lay people apparently feel about the ILPS demand Bills.

I like the nomenclature of Khongsai rather than Kuki, as some Khongsai Inpi uses it, and as we used to call all of them, such as Thadou Kuki, Zomi, Zou, Mizo, Hmar, Paite, Gangte, Mate, Vaiphe, Simte, phumate and others, in our childhood. It is lovingly attached to Meitei in the way Meitei-Pangal is closure than Muslim.

The recent Khongsai agitation was very impressive. ‘Seeing is believing’ – this is what St Thomas claimed to Jesus Christ. It’s now time to avoid sophistry and time to tackle avoidable sense of fooling. It’s now time for Manipur Government to develop hill districts as fast as it can, as it has done for capital Imphal.

Life is a constant struggle for survival. Meiteis, Khongsais, Tangkhuls and Kabuis are doing their bit. Why not? But we cannot go forward by fooling each other all the time. Even some insects such as mosquitoes that spread Malaria and Dengue, have woken up in Manipur after having been fooled with DDT for some time.

Scientists at Winchester in south England, have produced a chemical pheromone, which when sprayed, fool common male “clothes moths” into believing that male moths are females, and waste their time in chasing them rather than mating with females.

This was in response to a four year moth infestation in The Natural History Museum in London that was threatening some of its most prized exhibits.

This artificial sex pheromone – a chemical, when sprayed, dresses male moths as transvestite females and releases an odour to attract male moths. It thus fools male moths into thinking that some male moths are females and miss out on mating.

Since the system was introduced the number of moths in the museum has fallen by 50 percent. Overtime, less mating means less eggs are laid, less larvae hatched and less damage to the precious exhibits. But this is not however, a perfect protection.

Fooling the male moths to stay bachelor did not last long. The enemy soon realised and their babies kept devouring the displays in their glass cases, The Natural History Museum has now turned to human friendly wasps – tiny parasite wasps – “Trichogramma” to slaughter moth eggs en masse. I will come to this later.

These tiny cloth eating moths should not be confused with vegetarian moths in the garden, which often kill themselves flying into open flames.

There are over 160,000 species of moths. They evolved earlier than butterflies. Fossils have been found that may be 190 million years old. Moths are mostly nocturnal and they hold their wings horizontally at rest while butterflies hold their wings up vertically.

I am familiar with the small white cabbage moth. When I was small, Its caterpillars used to crawl out from our kitchen garden cabbage plot onto our veranda in summer, making me itch. My father used to kill them by putting them into a jar of paraffin. These caterpillars have urticariating hairs that stick on the bark, in foliage and others. When threatened they snap off the hairs that drift in the air. They can cause skin allergy (urticaria – swelling), runny nose and asthma.

During my childhood, my father and the eldest brother (both state engineers) used to bring out their winter woollen clothes that have been staked away all summer, for airing in the Sun. They smelled of naphthalene moth balls. In spite of it they often found some woollen suits with holes, chewed up by clothe-moths’ caterpillars.

Here in the UK, I see a very few clothe-moths in summer inside our house. In spite of lavender-smelling moth repellents we still find odd holes in woollen garments that have been stashed away for the summer. They can cause an economic blow. A £250 suit with a hole chewed up by moth larvae means a new suit to buy. The larvae love natural fibres such as woollen clothes and carpets in the dark atmosphere.

The clothes moth – “Tinea bisselliella” is the most common fabric eater. Actually, the adult moths do not eat clothes. It is their babies – the larvae caterpillars. Adults do not even have a mouth. Once they have become moths they have no time to eat. They simply mate without wasting time in eating. After laying an average of 40-50 eggs in 4-10 days in summer, and in 3 or more weeks in winter, the females die at some point (3-16 days). The males survive the females by about one month and continue mating. There are usually 2 generations a year.

The eggs are attached to cloth fibres by a sticky substance. The development time from egg to adult varies from one to three months, depending on temperature and humidity. The adult moth is about 7-8 mm in length with camel or off-white colour. The head has a tuft of reddish brown hairs. They are weak fliers and thus shun light. They would rather run rapidly than flying away to escape.

Mature larvae (caterpillar) after hatching out of eggs are 12-13 mm long with white or cream bodies and brown head capsule with no eyes. These are the ones that feed on fabrics. They will feed on wool, fur, cashmere, carpet, feathers, hair, and similar animal products to get proteins from keratin (insoluble protein like nails). They can eat and survive on any natural fibre, but If there is no food they will cut but not eat, through man-made fibres like the common polyester we use these days. The fibres the larvae eat eventually also end up becoming a part of the silken cocoon it spins for itself so it can become a moth.

The larval stage can extend from 1 month to 29 months if the conditions for it to pupate (to go into a case or cocoon) are not ideal.

When an adult moth female senses eg a wool sweater in the wardrobe, it naturally chooses it, as the best for its babies. Wool contains more moisture the larvae need with their food. The adult moths and their larvae are also attracted by dirty clothes, particularly ones dirtied with urine stains and sweat. Sweat contains not only moisture but salt and other minerals the larvae need to survive. The damage to clothes is generally in dark hidden locations, such as stacked piles of sweaters or blankets where the vapours from moth repellents cannot reach.

The Natural History Museum is now using Trichogramma for a frontal assault, so to speak, to give the enemy a taste of their own medicine.

Trichogramma are pale yellow parasitic wasps – among the smallest insects on this planet, having a wing span of 0.5 mm. Four or five of them will fit on a pinhead. Despite their size, they are like Gurkhas – efficient destroyers of moth and butterfly (leaf eater) eggs. They seek out eggs.

During their 9-14 day life, the female wasps will seek out and destroy about 50 pest eggs by laying at least an egg inside each pest egg. The trichogramma egg will hatch out into a larva, and it will consume the contents of the pest egg, killing the moth egg.

These parasitic wasps are cultured in America. They are bought and shipped from America as pupae in host eggs, ready to hatch as adults, glued on cardboard paper squares of 2.5 cm. Each disc has about 8,000 eggs. These are distributed in areas to be controlled. New adults will emerge in about 10 days.

Once out as adults by chewing holes in the host eggs they mate. The females use chemical and visual signals to locate target eggs to lay their eggs. When a suitable egg is found, an experienced female will go merrily to work for laying eggs. It will use antennal drumming, tapping on the egg surface, and also use the ovipositor (tubular egg laying organ) to determine if the egg has previously been parasitised.

Antennal drumming is also used to determine the size and quality of the target egg, which determines the number of eggs the female will insert. A single female can parasitise one to ten host eggs a day. Up to 5 parasite eggs may be laid in each moth egg about the size of a pinhead. One adult female can parasatise up to 50 moth eggs.

Trichogrammas of which there are 200 species, are widely studied for pest control. They can destroy 200 species of moths such as cabbage and apple moths and caterpillars.

Apart from these highly scientific methods there are the usual methods of controlling clothe moth infestation. They include periodic dry cleaning to get rid of moisture or laundering, proper storage, freezing, heating, fumigating with dry ice, trapping male moths with pheromone on a sticky surface, or pyrethrum insecticides. It is important to regularly inspect fabrics and closets for moths.

The writer is based in the UK