Conservation: How to... Identify and Handle a Moth Problem
Why do infestations occur?
Various species of moth will eat materials around the home, such as wool, silk, fur and feathers including furnishings, carpets, clothes and natural history items.
Moth larvae hatch from eggs and eat any organic material around them to increase in strength and size. Once large enough they will form a cocoon and metamorphose into the adult moths. As an adult, a moth may stay put if there is enough food and potential mates – worsening an existing infestation. Alternatively they will fly to find a new location (typically during the warmer summer months) possibly starting a new infestation.
Moths like dark, undisturbed places to breed and eat; they are often to be found in wardrobes, drawers, cupboards and lofts. They can also prefer warm, damp environments.
How do you know if you have a moth problem… what are the tell-tale signs?
It is most likely that you will identify an infestation by the damage that has been caused rather than by seeing the pests themselves. It is therefore important to recognise the signs.
With most pests finding holes in items where the pests have been feeding are the most obvious clue. Frass - the name for insect poo and which looks like clumps of small grains – will often be found near the holes in an item or on the surface beneath where it is stored.
Additionally with moth infestations cocoons and webbing (silk woven over the area the lava is feeding) are sometimes left behind. The cocoons may be hard to see as they are often made from the material of the item which is infested.
Moths will often feed in the creases, folds and seams of clothing and curtains, preferring to hide away from light, remember to check items thoroughly!
How do you fix a moth problem?
• Empty the affected area and check all items.
• Check for other items that may be affected in the storage area and possible sources of the infestation. Look in air vents, up chimneys and other areas that might otherwise be overlooked.
• If a moth infestation has been found, check to see if the carpet or curtains in the area are affected.
• If one item is infested then the problem can spread to others. To avoid allowing an infestation to develop check any items you bring into your home. Anything that might be infested should be quarantined until you are happy it is safe.
• Clean the affected area thoroughly with a hoover and small soft paintbrush brush to remove any insects/ webbing/ eggs. Remember to empty and clean your hoover afterwards!
Before undertaking any treatment carefully consider the options and in particular speak to a conservator if the item is old, valuable or holds great sentimental value.
A variety of techniques are offered for removal of a moth problem (killing the insects and their eggs or larvae):
• Fumigation- using chemicals. If carried out without training this poses a risk to both yourself and potentially the items of clothing etc you are trying to rescue.
• Anoxia- the removal of oxygen from the area around the item of clothing when wrapped in plastic. This is difficult to ensure effectiveness especially for a non-professional.
• Freezing- It is vital to determine that the temperature reaches below -20 in your freezer for it to be effective, the items must also be rapidly frozen otherwise freezing may only put the insects to sleep. Use a thermometer, digital ones are safe and relatively cheap, to monitor the temperature and freeze for 1-2 weeks.
• Heat: for normal household items of clothing, washing and tumble-drying can be enough to eliminate the problem. This is not recommended for delicate or highly prized items.
Although repellents/ deterrents are available it can be very difficult to ensure their effectiveness as they often utilise pheromones which generally target one species of moth and then only the males.
Integrated Pest Management (IPM) is a holistic approach used successfully in Museum Collections and can be transferred to the home:
Monitor storage spaces and clean at regular intervals to help catch and remove potential infestations. Sticky or blunder traps can be used to monitor activity in vulnerable areas.
The development and breeding of potential of pest insects is slowed if the temperature can be kept below 15 degrees Centrigrade. Insects also prefer higher humidity levels so reducing damp and lowering the humidity in the home to below 60% RH you can prevent breeding.
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