Moths belong to the insect order Lepidoptera, an order which is comprised of butterflies and moths. There are thousands of species of moths, of which some are important agricultural and stored product insect pests. Prevalent throughout Canada, pest moths are relatively destructive insects that cause various types of damage depending on the species. While some moths damage clothing, carpets, upholstered furniture, wall hangings, and even museum artifacts, other moth species are stored-food pests that infest pantries, granaries, and warehouses.
The casemaking clothes moth and the webbing clothes moth, for example, are two common species of fabric pests found in Canada, while a good number of the pyralid moths such as the meal moth complex (including the Indian meal moth and other meal moths) also enjoy a widespread presence in the country and attack stored food. Related to butterflies, moths are nevertheless distinguishable by their feathery antennae of various shapes, stouter bodies, and typically duller colours.
Appearance / Identification
Moths vary in size and appearance from species to species. For instance, the Indian meal moth is relatively small and measures around 9 mm in length, but has a wingspan reaching up to 16 mm. These moths stand out from other pantry-pest species due to the reddish-brown or copper sheen on their forewings.
Similarly, the webbing clothes moths have a buff or gold colouration, with reddish-gold hairs on the top of the head and around the wings. The fabric pests tend to range in size from 6 to 8 mm, with a wingspan extending as far as 12 mm. Casemaking clothes moths boast dark spots on their wings, which distinguishes the species from webbing clothes moths.
Webbing Cloth Moth
Moth Pupa Image
Moths can be found throughout the Canadian provinces, but they tend to stay close to food sources. Adults live near their breeding sites as developing moths need a consistent food source to grow and mature. Species that feed on stored food products are commonly found in food processing and handling facilities as well as in homes. Meanwhile clothes moths often infest homes, museums, and fabric handling facilities.
Most species of moths feed on nectar and sap as adults. The larvae, often referred to as caterpillars, are the ones which inflict damage by attacking stored foods or fabrics. The stored-food pest species consume various common pantry items, including seeds, grains, cereals, dehydrated herbs, and dried pet food, while clothes moths can eat through wool carpets and rugs, clothing, upholstered furniture, furs, and all sorts of synthetic and cotton blends.
Life Cycle / Reproduction
Moths undergo complete metamorphosis where eggs are laid on suitable sources of food. The eggs hatch into larvae, commonly referred to as caterpillars, and they undergo a series of larval transformations before pupating and becoming adults. The length of development time is dependent on temperature, humidity, and diet. In most cases, it takes about one to two months or more depending on species. Before pupating, larvae molt up to 4 – 5 times depending on the temperature of the environment and the availability of food sources. Pupation lasts up to 10 days in warm weather but may continue for longer periods of time during the winter months. When adults finally emerge, they are sexually mature and begin the reproductive process anew.
Problems Caused by Moths
Pest species of moths can cause damage to dry stored products, especially foods and fabrics, and even museum display pieces. The insects cause the bulk of the damage during the larval stage of the lifecycle. Some species also construct pupation cocoons, which creates additional damage. Furthermore, accidental ingestion of the cocoons or the larvae themselves may result in gastro-intestinal irritations and upset stomachs.
Detection / Signs of Infestation
Physically seeing adult moths or larvae are the most common way of identifying an infestation problem. Another sign of a moth infestation is the silk webbing left by the larvae of certain species while feeding. Other species, such as clothes moths, leave behind visible evidence of their presence on fabrics and textiles. Clothes moths tend to damage fabrics in less noticeable ways by focusing on the cuffs and collars of apparel, the crevices of upholstered furniture, and the carpeted areas underneath home furnishings. The pests typically attack old, dirty, or stained items.
Ramping up sanitation efforts is the best way to prevent moth infestations from occurring. Store grains and other pantry items in airtight containers, vacuum up spilled foods promptly and regularly, and use both heat and cold where applicable to help destroy burgeoning infestations. Dry cleaning clothes and steam cleaning furniture may also effectively keep certain species from infesting and reproducing.
Control / Removal
Use of appropriate pheromone traps can help with the detection and control of moths from homes and other structures. For pantry-invading species, exposure to extremely high or low temperatures will kill the developing larvae and stop the threat of infestation. Home cleaning agents, on the other hand, have proven to be less than effective. An appropriately labelled insecticide product may be used to control adult moth populations. It is important to read and follow label instructions for safety. For severe infestations, consult a pest management professional to control and eliminate the moth infestation.
Giant Silk Moths
Indian Meal Moths