In this article we will briefly delve into the two main species of food/pantry moth commonly found in the UK, the Mediterranean flour moth and the Indian meal moth. Although mostly seen independent of each other infestations can in cases be built up of both species.
'Pantry moth' or 'food moth' is shorthand for any moth found feeding on grains within a kitchen or food production environment. Once these moths have arrived they are quick to establish and start through the life cycle, multiplying quickly and feeding on many stored foods. Food/Pantry moth webbing will be found in multiple locations, inside food containers, on canned goods and attached to the underside of lids, the darker and more undisturbed a location the better the conditions for food/pantry moths and the higher the chances of infestation.
Mediterranean Flour Moth (Ephestia Kuehniella)
Colour: Light Grey
Size: 6-12m
Wingspread: 23mm
Key Features: The wings are marked with two zigzagging lines, dark and fuzzy in appearance, with a dirty-white pair of hind wings.
Life-cycle: takes approx. 10 weeks.
Reproduction: The female moth lays between 100 to 600 white eggs within their preferred food source with the eggs commonly attached to the food.
Food Source: commonly feeds on flour, grains, cereal, pet food, beans, chocolate and dried fruits.
Description: The Mediterranean Flour Moth is larger than the Indian Meal Moth. Both moths share a similar pattern of development and will cause similar damage. The main difference to the Indian Meal Moth is that the larvae of the Mediterranean Moth live and feed in the small silk tubes they spin. The webbing and matting of the larvae often cause the main damage, through contaminating foods or clogging machinery. After being laid it usually takes three days for the eggs to hatch into small white/pink larvae with a dark coloured head; small black spots on the body will often be visible. The larvae immediately start to spin silken tubes in which they will remain in until fully mature, usually within 40 days. The larvae will then leave their feeding area to look for a harbourage to make a silken cocoon and turn into red-brown pupae, after 8-12 days in situate they will emerge an adult moth.
Indian Meal Moth (Plodia interpunctella)
Colour: Bronze-grey
Size: 8-10mm
Wingspread: 16-20mm
Key Features: the outer half of the fore wings are bronze or dark grey in colour, with the upper half being a yellow-grey colour with a dark band between the two.
Life-cycle: 1-10 months (depending on conditional factors, such as temperature)
Reproduction: The female moth lays between 50-400 eggs on food, the eggs are usually less than 0.5mm.
Food source: Commonly a grain feeding pest, feeding on cereals, bread, pasta, rice, dried fruits and nuts.
Description: The Indian Meal Moth is smaller than its cousin the Mediterranean Flour Moth, with which it shares a similar pattern of development. The Indian Meal Moth is the most common moths infesting stored food stuffs. The females will begin to lay eggs on food within three days of emerging, laying eggs over a period of 1 to 18 days. The eggs hatch within 14 days, after which time they will start to build silk and frass tunnels in which they live and feed. Infested food will often seem to be webbed together due to this stage of the life-cycle. The larvae stage can be anywhere between 2 to 41 weeks depending upon the temperature conditions in their local environment. Indian Meal Moth larvae are commonly known as ‘waxworms’ and are usually around 12 mm long, off white in colour with brown heads. The pupal stage is usually 2 weeks in favourable conditions. After which they will emerge an adult moth.