Abstract

Woolen and pashmina products such as shawl, blankets are more susceptible to moth attack. The damage to the woolen textiles by moth larvae throughout the world is estimated to cost millions of dollars every year.  The damage by textile pests to the long lasting items such as carpets, blankets and upholstery fabrics can be very costly not only to the consumer, but also to the textile manufacturer. The main objective of this paper is to understand all about the moth larvae. So, this review paper covers the different types of moth larvae along with their scientific details, specifications & also how these moth larvae damage the different woolen textiles is discussed.

Keywords: Wool, Moth Larvae, Scientific specifications, Damage.

1. Introduction

Fabrics can be damaged by textile pests within a few weeks of initial infestation.  While moth damage is liable to occur in wool at any time and in fact bales of wool as they arrive, they are frequently infested, the damage occurs mainly in storage.  Further, during the manufacture,  the wool is kept moving passing from one process to another and except when it is stored in top form is unlikely  to be attacked.  But in stores and in home matters are very different. Textile pests with short life cycles can produce insect populations within 18 months and can seriously damage unprotected carpets and floor coverings.  The insects usually remain undetected until the damage has occurred.

The better conditions that exist in modern stores reduce the likely hood of moth attack, but it is surprising to know how easy it is for damage to reach very considerable proportions before it is noticed. In tropical countries like India, people use the woollen textiles during the winter season regularly and for rest of the time these articles are kept aside, and during this time the infestation may occur unless suitable precautions are taken to protect them.  Carpets and furnishing cloths are particularly liable to be attacked causing enormous damage to chairs, sofas and window hangings.  Far and away the best precaution that can be taken in the first place is to buy articles made from materials that have been moth proofed.

The damage that can be caused by the moth larvae is almost fantastic. Clark¹and Hartley, Elsworth and Barritt² have estimated the damage caused by a single larva to be 92.5 pounds in one year and 100 pounds in 280 days respectively.  Meckbach³ estimated the world’s total loss at 22.5 million pounds per annum. The real financial loss  to  the  user  is  clearly  much  higher  because of  damage  to  the costly   woolen  articles.  Mosher⁴ has quoted the estimates of loss from 200 to 500 million dollars a year.  It will be clear that serious attention has to be given to the damage caused by moth infestation.

Some of the most important insect species which create enormous damage to the woolen textiles   are  the case bearing clothes moth (Tinea pellionella) and clothes moth (Tineola bisselliela), along with  various numbers of carpet beetle families including furniture carpet beetle and black carpet beetle.   The damage caused by carpet beetle  account for more than half the total amount of insect damage to the fabrics and it is essential  to  look for a chemical  for  providing protection against the carpet beetles.

2. Types of moths

There are six varieties of moths which cause considerable damage to wool, of which four are clothes moth and two are house moths.

1. A) Clothes moths

1. The Common Clothes Moth, Tineola bisselliella



2. The Case-bearing Clothes moth, Tinea pellionella



3. The Tapestry Moth, Tricophaga tapetzella



4. The  Large Pale Clothes Moth, Tinea pallescentella

The ability of this larva to digest wool is an accomplishment which although they share with some beetles is most uncommon.  Larger animals are quite unable to digest and excreta of carnivorous animals frequently contain undigested remnants of hair and fibres.  The hair and fibre are keratinous bodies like wool.   The adult winged insects, whether Clothes moth or House Moth do not eat wool.  Their function is purely reproductive. They lay eggs and the eggs hatch into grubs or larvae, which do eat wool and cause tremendous damage.  The Clothes moth belong to the group Tineidae (Latin tinea = moth book worm), and on account of their very small size compared to the average run of moth they are known as micro Lepidoptera.  The House moth belongs to the group Ecophoridae.

2.1 Clothes moths

2.1.1 The common clothes moth

The common clothes moth Tineola bisselliella is also known as the webbing moth from its habit of making web with wool fibres, and it is also known as the naked cloth moth. It is dull coloured creature with two pairs of uniformly pale buff wings similar in shade to tussah silk and fringed with scales. Like all other moths the life cycle comprises of four stages - egg, larva, pupa and moth and the time taken for the cycle varies enormously according to the conditions of temperature, humidity and diet available.  The limits are about 48 days minimum and four years maximum. The larva grows to a length of half inch and in the process moulds or sheds its skin seventeen times.  During this growing stage it surrounds itself with cylindrical structure made from fibres and gum; the structure being called as gallery and it feeds from it projecting the head.  Over a period of time the larva forms a silk like cocoon from fibres and its own excrement.  The time taken for this various processes varies considerably, but as the egg can hatch within a week serious trouble results in.

Binomial name: - Tineola bisselliella⁵

Scientific classification

Kingdom: Animalia

Phylum: Arthropoda

Class:   Insecta

Order: Lepidoptera

Family:Tineidae

Genus: Tineola

Species: T. bisselliella

2.1.2 The case- bearing clothes moth

The case bearing clothes moth Tinaea pellionella also known as Fur moth and as a single spotted clothes moth is in its larval stage equally as destructive as clothes moth.  Even during moulting which the larva undergoes periodically it does not leave its case and for feeding purpose it simply protrudes its head and thorax.  The life cycle of this moth is similar to that of the clothes moth -i.e. egg, larva, pupa and adult moth and in its case too, the time taken for life cycle to be completed is variable depending on the conditions.  Under favorable conditions three generations of case bearing moths may appear in a year.

Binomial name: - Tinea pellionella⁵

Scientific classification

Kingdom: Animalia

Phylum: Arthropoda

Class:   Insecta

Order: Lepidoptera

Family: Tineidae

Genus: Tinea

Species: T. pellionella

2.1.3 The tapestry moth, Trichophaga tapetzella

The tapestry moth, Trichophaga tapetzella, also known as the white tip clothes moth, usually attacks heavy fabrics such as tapestries, carpets and feltings.  In case of pile material its larvae burrow to the bottom of the pile and destroy the warp threads so that the pile falls out.  They are specially fond of rabbit wool.  Carpets, furniture, tapestries, felts, furs and skins are attacked by them.  When the grub is fully grown a cocoon is made and finally the moth emerges to fulfill the reproductive function and restart the life cycle.

Scientific classification

Kingdom:- Animalia

Phylum:- Arthropoda

Class:- Insecta

Order:- Lepidoptera

Family:- Tineidae

Genus:-Trichophaga

Species:-T. tapetzella

Binomial Name:-  Trichophaga tapetzella⁵

2.1.4 The large pale clothes moth

The Large pale larvae are shining white when fully grown and about half inch in length.  They are observed in humid climates and eat not only wool, hair and skin, but also vegetable matter such as spoiled wet grain.  The life cycle is similar to that of other moths.  They occur in Great Britain (Southern Scotland).

3. Clothes moth life cycle

Like all other moths, clothes moth also undergo four distinct stages; egg, larva, pupa, and adult stage. Females of clothes moth lay an average of 40 to 50 eggs over a period of 2 to 3 weeks and die once egg laying has been completed. Males outlive females and continue to mate during the remainder of their lives. Eggs are attached to threads of fabric with an adhesive secretion; they hatch in 4 to 10 days during warm weather. Larvae molt from 5 to 45 times, depending on indoor temperatures and type of food available. The larval period lasts from 35 days to 2-1/2 years. Larvae are shiny white with a dark head capsule. They spin webbing as they feed and may partially enclose themselves in a webbing cover or feeding tube, depending on species. Excrement of the clothes moth may contain dyes from the cloth fibers being consumed and thus be the same color. When they are ready to pupate, larvae wander away from their food source to find crevices. With the case making clothes moth, pupation takes place inside the case— usually on the fabric.

Pupation lasts from 8 to 10 days in summer, 3 to 4 weeks in winter. Heated buildings enable clothes moths to continue development during winter months. Generally, developmental time for the clothes moth from egg to egg is between 4 to 6 months, and there are generally two generations a year. A female moth can lay around 100-400 eggs at a time. The eggs take about 4 to 10 days to hatch, depending on temperature and humidity.

After hatching, the larvae come out and start feeding on the available resources such as woolen clothes, silk, carpets, etc. Larval stage is the most destruction stage of a clothes moth’s life. The moths may take up to 30 months to molt into pupal stage, until they find their favorable conditions to pupate. They will happily persist through winter, spring, and summer, eating your clothing and waiting for the right conditions to turn into adult moth.

Once they get their favorable condition, they will enter into the pupation stage in which they will spin a cocoon to transform into an adult. This process can take up to 10 days.

The adult clothes moths will mate and lay eggs within a few days. The female moths die within two weeks of depositing eggs (3-16 days), whereas the males may survive for almost a month.

4. Clothes moth identification & special characteristics

The webbing clothes moth is the most common fabric moth. Adults are golden colored with reddish golden hairs on top of the head. Wings, with a span of about 1/2 inch, are fringed with a row of golden hairs. Because the moths are weak flyers and not attracted to lights, they are usually found very close to the infested items, such as in dark areas of closets. Don't confuse the clothes moth with the common food- and grain-infesting moths that are frequently seen flying around the house. At rest, clothes moths are only about 1/4 inch in length, whereas most food-infesting moths are about 1/2 inch in length. Clothes moths are relatively easy to catch when they land.

When examined with a hand lens, little tufts of hair are evident on their heads—food and grain moths do not have these tufts. Clothes moths usually only fly around the immediate area of the house where the infestation is found, and their flight pattern is distinctive: they tend to flutter about rather than fly in a direct, steady manner like the food infesting moths.

Case making clothes moths are similar in size and appearance to webbing clothes moths. The wings of the case making clothes moth are more brownish than those of the webbing clothes moth and have faint dark colored spots. Hairs on the head are lighter colored than those of the webbing clothes moth. Larvae of both species are nearly identical, except that larvae of the case making clothes moth always carry a silken case with them as they feed. They never leave this silken tube, but enlarge it as they grow. They feed from either end and retreat into it when disturbed. This case takes on the coloration of the fabric eaten by the larvae.

Clothes moths are afraid of light. So, they prefer closets, basements, and other dark and undisturbed places. They do have wings but they prefer not to fly, even when they are disturbed. Adult clothes moths do not cause any damage to the fabric. It is the larva that causes all the damage by feeding on fabrics. The larvae can be found under the hidden parts of the clothing such as cuffs and collars.

5. The damage caused by moths

Clothes moth and carpet beetles feed on wool in all conditions.  The bales of wool as they arrive in mills in India from Australia have often moth in them and at any stage throughout its manufacture during sorting and blending, after scouring, carding, back washing, combing, in the top or later in the roving or in the spun yarn, dyed or undyed, the moth will attack wool, given the chance, and the chance occurs whenever the wool is unsuitably stored or is neglected.

Carpets if stored for only a few months stand a good chance of infestation unless special precautions to exclude or kill moths are taken.  Clothes and carpets that are in the use are not often attacked, but furniture may be, and if once the stuffing is infested the moths will breed and multiply and eventually emerge, to the surprise and dismay of the owner, through the surface.  Many times an overcoat that has been put away for the summer has been found when put back into use to be moth eaten.  It has to be remembered that the moths, or strictly their larvae need to have eaten only a very small quantity of wool to make a garment or a chair unsightly or greatly depreciated in value.  Tapestries, coarse heavy fabrics and carpets are prone to attack, particularly by the case bearing moth.  Rabbit wool seems to be particularly attractive to moths and such imported costly material has been seen to be infested with the Tapestry Moth causing high financial losses to the manufacturer.

The larva is the damaging stage of the clothes moth. Both species feed on wool clothing, carpets, rugs, upholstered furniture, furs, stored wool, animal bristles in brushes, wool felts in pianos, and fish meal in fish food. Synthetics or fabrics such as cotton are fed on if they are blended with wool. Larvae may use cotton fibers to make their pupal cases. Damage generally appears in hidden locations such as under collars or cuffs of clothing, in crevices of upholstered furniture, and in areas of carpeting covered by furniture. Fabrics stained by foods, perspiration, or urine are more subject to damage.

Mosher⁸ reported that he had encountered silks and rayons damaged by clothes moths. It seemed to be well established that if garments or fabrics are made from mixture yarns - e.g., wool and viscose - some of the viscose is eaten along with the wool, but it is not digested.  Carpet beetles according to Mosher eat all animal fibres, including silk, with avidity and also such materials as glue, casein and albumen which are sometimes used as sizes on rayon and cellulosic yarns and fabrics.  Probably most if  not all the cases where clothes moth have been reported attacking silk or other fibres which are not animal hairs have been due to the real attack being on a size or finish on the yarn or fabric.  It seems to be fairly well established that silk is immune from its attack.

The description given above relates to some of the wool feeding species which damage woollen textiles and articles.  It would now be appropriately understood that how serious is the issue of protecting wool from the damage caused by the different species of moth.  The wool is a premium fibre and also has a great export potential, the importers aboard also demand for properly moth proofed material.  In fact moth proofing has become one of the parameters for judging the qualities of the woollen fabrics like apparels, knitwears, furnishing cloths and carpets manufactured from wool.  The International Wool Secretariat⁹  in U.K. and International Organization for Standardization ¹⁰  have developed methods for assessing the performance of the untreated  fabric along with the fabric which has been treated with the moth proofing material. Woollen materials has an export obligation, certain moth proofing specifications have to be met in line with the internationally accepted methods of tests.

6. Remedies ¹¹

Clothes moths can be controlled by a variety of methods, including periodic dry cleaning or laundering, proper storage, freezing, heating, or fumigating with dry ice, trapping, or using an insecticide. If humidity can be kept low inside buildings, an environment that is not suitable for clothes moth development will be created. Building construction that is free of many tiny cracks and crevices also contributes to fewer clothes moth problems. Good housekeeping practices are also important. Although most people can control clothes moth problems themselves, some infestations are best handled by a pest control applicator which has the equipment, materials, and experience necessary to deal with a difficult control job.

6.1 Preventing or reducing infestations

Periodically clean areas of a home that may harbor clothes moths to prevent or control infestation. Those areas include many seldom-cleaned spots, such as: under heavy pieces of furniture; along baseboards and in cracks where hair and debris accumulate; closets, especially those in which woolens and furs are kept; and heaters, the areas behind them, and vents. The vacuum cleaner is the best tool for most of this cleaning. After using it in infested areas, dispose of the bag contents promptly; they may include eggs, larvae, or adult moths. Clothes moths may first become established on woolen garments or scraps stored for long periods. If such articles are to be saved, they should be stored properly, or periodically hung in the sun and brushed thoroughly, especially along seams and in folds and pockets. Brushing destroys eggs and exposes larvae. Larvae are strongly repelled by light, and will fall from clothing when they cannot find protection.

6.2 Dry cleaning and laundering

Dry cleaning or thoroughly laundering items in hot water (temperature above 120°F for 20 to 30 minutes) kills all stages of insects. This is the most common and effective method for controlling clothes moths in clothing, blankets, and other washable articles. (Because many woolen garments should not be washed in hot water, dry cleaning may be the only suitable cleaning option.) Keeping fabrics clean also has another advantage: insects are less likely to feed on clean fabrics than on heavily soiled ones.

6.3 Protecting items in storage

Clothes moths often damage articles that are not stored properly. When storing susceptible items, be sure they are pest-free and clean, and place them in an airtight container. Insect repellents can be placed in the storage container. A new product made from lavender oil is available as a gel-filled sachet that can be used inside drawers and storage boxes, or hung in closets. Research studies are currently underway regarding the efficacy of this product.

Moth balls, flakes, or crystals containing naphthalene or paradichlorobenzene are also available for protecting clothes in storage. These materials are toxic and must be kept away from children and pets. They also leave an unpleasant odor on clothes and other cloth objects. If placed in contact with plastic buttons, hangers, or garment bags, they may cause the plastic to soften and melt into the fabric. As these chemicals evaporate, they produce vapors that, in sufficient concentration, will slowly kill insects. The vapors build up to the required concentration only in an airtight container. If the container is not airtight, the chemicals only weakly repel adults and any larvae already on clothes continue to feed.

Questions are often raised as to the effectiveness of cedar chests and closet floors made of cedar. Aromatic eastern red cedar, Juniperus virginiana, contains an oil that is able to kill small larvae, but it does not affect large larvae. After several years, however, cedar loses this quality. Having the chest tightly constructed is more important in the long run than the type of wood used to make it.

6.4 Freezing and heating

Clothes moths can also be controlled by heating the infested object for at least 30 minutes at temperatures over 120°F, freezing the object for several days at temperatures below 18°F, or fumigating with dry ice (see "Household Furnishings").

6.5 Trapping

Trapping is a relatively easy-to-use technique that helps to both detect a webbing clothes moth infestation and to reduce it. Pheromone traps are available to trap the webbing clothes moth, but not the case making clothes moth. Pheromones are chemicals (in this case a sex attractant) produced by an organism to affect the behavior of other members of the same species. The sex pheromone attracts male moths into the trap where they get stuck on the sticky sides. Because the pheromone specifically attracts clothes moths, other moth species will not be attracted—conversely, webbing clothes moths will not be attracted to pheromone traps for other species such as grain-infesting moths. Pheromone traps for clothes moths are available from major hardware stores.

Place traps in closets and other areas where clothes are stored. Trapping not only allows you to detect the presence of webbing clothes moths but also provides some control because trapped males cannot mate. However, if you trap moths, you should also take other measures such as dry cleaning or laundering to protect clothes that were exposed to the moths.

6.6 Using insecticide sprays

If clothes moths are detected, articles that cannot be dry cleaned, laundered, heated to temperatures over 120°F, frozen, kept in cold storage, or fumigated with dry ice  can be sprayed with an insecticide. Find a product that lists clothes moths on its label and follow the directions exactly. Insecticides for clothes moths usually contain pyrethrins, which provide quick knockdown of clothes moths, and most can be sprayed directly on fabrics if needed (in situations where fabrics cannot be laundered or dry cleaned). Pyrethrin insecticides do not leave persistent toxic residues, which makes them more suitable for clothes moth control in many cases than many other products.

Some insecticides have an oil base. Do not spray them on silk, rayon, or other fabrics that stain easily. Do not use them around open flames, sparks, or electrical circuits. Do not spray them on asphalt-tile floors. Use only lightly on parquet floors. On linoleums, first spray a small inconspicuous area and let it dry to see if staining occurs.

Widespread or heavy infestations often require the services of a professional pest control applicator.

6.7 Special Situations

Rugs, carpets, furs, and household furnishings require special attention for protection from clothes moths. Rugs and furnishings made entirely of synthetic fibers are not affected. This includes most wall-to-wall carpeting

7. Conclusions¹²

Woolen and pashmina products such as shawl and blankets, lohis are kept for longer period in the factories, ware houses, shops and home; there is always the chance of the moth attack. So, the damage to the woolen textiles by moth larvae throughout the world is estimated to cost millions of dollars every year & causes decrease in the use & consumption of woollen textile. In all woolen textile materials, carpets are the most susceptible to the attack by larvae of certain moth, notably Tineola Bisseliella & few species of beetle because the hidden parts of some carpet installation provide the warm dark, undisturbed environment that such insects prefer. Moth larvae tended to breed in carpet & migrate from there to damage expensive clothes. Hence, it is necessary to understand all about the moth larvae & subsequently to use moth repellent agent for woolen textiles.

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