Moth infestations cause damage exclusively during the larval stage, a small, caterpillar-like grub that hatches from eggs laid by the adult female moth. Household infestations typically involve two types: Clothes Moths, which feed on natural fibers like wool and silk, and Pantry Moths, which contaminate stored dry goods such as grains and cereals. The adult moths are generally harmless, but their presence signals a reproductive cycle that must be broken. Eradicating a moth problem requires finding and destroying the hidden larvae and eggs, followed by active killing methods and preventative measures.
Identifying and Eliminating the Infestation Source
Stopping an infestation begins with finding the source, which differs based on the moth type. Clothes moths prefer dark, undisturbed areas, so inspection should focus on the backs of closets, under furniture, and in storage containers holding wool, fur, or feather products. Pantry moths are found in the kitchen, often within loosely sealed containers of flour, dried fruit, nuts, or pet food.
Once the source is identified, physical removal of the eggs and larvae is required for immediate control. Heavily infested food or fabric items that cannot be salvaged must be immediately discarded outside the home in sealed bags. All surrounding surfaces, including shelves, drawers, and carpet edges, should be thoroughly vacuumed to remove hidden eggs, shed larval skins, or cocoons.
The vacuum bag must be immediately sealed and disposed of outdoors to prevent trapped life stages from crawling back out. Washable garments and linens must be laundered in hot water, exceeding 120°F (49°C), to kill all eggs and larvae. For non-washable fabric items, dry cleaning is an effective alternative, as the solvents used are lethal to all moth life stages.
Active Killing Methods: Traps and Temperature Control
Active killing methods target both adult moths and destructive larvae through non-chemical means. Pheromone traps are effective for monitoring and controlling the adult population of both clothes and pantry moths. These traps use a synthetic sex attractant pheromone released by the female moth, luring the male moths onto a sticky surface.
By capturing adult males, these traps disrupt the reproductive cycle and prevent the laying of new eggs. Pheromone traps only target flying adults and do not kill existing larvae causing damage. Other sticky traps, which lack pheromones, can also be placed in areas of activity to capture wandering adults and larvae.
Temperature control is an effective method for killing all life stages within items.
Extreme Cold Treatment
Extreme cold can be used for sensitive fabrics or dry food products by placing them in a sealed plastic bag and freezing them at 0°F (-18°C) or below for a minimum of 72 hours. For garments, a period of up to two weeks is often recommended to ensure the cold fully penetrates the item.
Extreme Heat Treatment
Conversely, extreme heat is lethal to moths, with temperatures above 120°F (49°C) killing all life stages within 30 minutes. This thermal treatment can be applied by tumble drying infested items on high heat or by using a clothes steamer or heat chamber. The speed and certainty of thermal methods make them a preferred choice for immediate eradication within a specific item.
Using Chemical Treatments Safely
Chemical treatments offer a targeted approach to moth eradication but must be used with caution. Mothballs, flakes, and crystals contain volatile chemicals, typically naphthalene or paradichlorobenzene, which kill moths and larvae by releasing a toxic vapor. These products are only effective when used in tightly sealed, airtight containers where the fumes can build up to lethal concentrations.
Using mothballs in open closets or drawers is ineffective for killing pests and exposes the home environment to fumes toxic to humans and pets. Residual insecticide sprays containing synthetic pyrethroids, such as permethrin or deltamethrin, can be applied to non-washable surfaces like carpet edges, crevices, and closet walls. Pyrethroids offer a residual effect, meaning they continue to kill larvae and moths that crawl over the treated surface after application.
A simpler pyrethrin-based spray provides a quick knockdown effect but lacks long-term residual activity. Natural deterrents like cedar and lavender function as repellents, not killers. The aromatic oils in cedarwood, such as cedrol, are unpleasant to adult moths and may deter them from laying eggs, but they will not eliminate an existing infestation of feeding larvae.