The Indian meal moth

The Indian meal moth

The Indian meal moth

Latin: Plodia interpunctella.

A beautiful little moth with eye-catching colours. The elytrons’ inner third is light gray, while the rest is reddish brown. The larvae are yellow-white with dark brown heads. The larvae are 12 – 13 mm long when ready for pupation. The Indian meal moth probably originated from Europe, but can now be found everywhere. The moth is a troublesome pest in warm countries, especially in places with dried-fruit industries. The larvae damage dried fruit, nuts and almonds, and exceptionally cereals and cereal products. The larvae sometimes occur as “worms” in chocolate.

Season for Indian meal moth

Season for Indian meal moth

The female begins to lay eggs three days after the change to the adult moth. Over the next 14 days she lays about 500 eggs. The development time from egg to adult depends on food and temperature. Under optimal conditions at 25 °C, it takes just 35 days to fully develop. In unheated warehouses, progress is slow, and may only produce two generations per year. Larvae ready for pupation often crawl far away from whatever they matured in. The pupa, which is approximately 7 mm long, is completely entangled in a rather thick, white silk cocoon.

The brown house moth

The brown house moth

The brown house moth

Season for the brown house moth

Season for the brown house moth

Latin: Hofmannophila pseudopretella.

This is quite a large moth, usually 1.5 cm long. The wings are almost bronze-brown and the elytrons have small but distinct dark spots. The largest of the larvae are about 2 cm in length. They are whitish except for the head which is dark. All types of plant material can be infested by the brown house moth. The larvae can also live in dry milk; they can fester in damp corks in dank wine cellars and destroy cork flooring, leather and woollen textiles. The brown house moth is common in the wild, where it feeds on both leftovers of feed as well as nesting material for birds’ nests.

Life cycle for the brown house moth

Life cycle for the brown house moth

A female brown house moth can lay 600 eggs during its lifetime. The development from egg to adult at 25 °C lasts 3 months. At 15 ° C, it takes 7 months and at temperatures below 13 ° C development stops completely. The brown house moth larvae are very sensitive to dehydration and cannot pursue their development if the humidity is consistently below 80% RH. Therefore, the safest and most reasonable precaution against brown house moths is to provide dry storage conditions.

Tropical warehouse moth

Latin: Ephestia cautella.

The tropical warehouse moth also belongs to the chocolate moths and is very similar to the previous two species, both in appearance and way of life. The tropical warehouse moth has higher demands for temperature and is particularly prevalent in tropical and subtropical regions. The tropical warehouse moth can attack virtually all stored food – with the exception of meat and tobacco. The tropical warehouse moth cannot survive in unheated warehouses in non-tropical countries and will eventually die if the temperature drops below zero. In many cases, there are numerous tropical warehouse moths in imported goods, but replaced later by the warehouse moth when the goods arrive at warehouses in Europe.

The warehouse moth

Warehouse moth

Warehouse moth

Season for the two chocolate moths

Season for the two chocolate moths

Lat: Ephestia elutella – Also called cocoa moth or tobacco moth.

It belongs to the group of moths called chocolate moths. The warehouse moth is similar to the Mediterranean flour moth. The warehouse moth is common in warehouses and households throughout the temperate part of the globe. It infests, among other foods, grain, seed, feed, dried fruit, almonds, nuts, cocoa beans and chocolate products. Warehouse moths can also do damage to tobacco stocks.

Females lay about 300 eggs, the majority during the first four days of their lives as adult moths. The adult moths do not live very long. 2-3 weeks at room temperature and at 25 ° C it lives approximately 9 days.

However, the larvae have a slow development. At room temperature, they develop in 80 to 206 days, depending on their diet. The full-grown larvae measure 12 mm. They become restless and leave their food to wander around for up to three days before they find a place to pupate. They seek upwards and they usually end up in a suitable place at the top of a wall or on a ceiling.

In unheated warehouses, the larvae will go into hibernation in the autumn, this is the so-called diapause, and then they will not pupate until the following year. The pupal stage lasts 2-3 weeks.

The Mediterranean flour moth

Mediterranean flour moth

Mediterranean flour moth

Season for flour moths

Season for flour moths

Latin: Anagasta kuehniella or Ephestia kuehniella.

The rather narrow wings have a span of 20-25 mm. Forewings are leaden with dark, zig-zag-shaped transverse lines and dots. The rear wings are pale gray with long fringes on the back edge. The Mediterranean flour moth larvae which can be 15-19 mm long, are white, pink or bright green.

The Mediterranean flour moth probably comes from the Middle East. In 1877 it was found for the first time in Europe in a consignment of wheat from North America and it has since spread across the world. In many countries, the Mediterranean flour moth is in virtually all establishments where flour and other grain products are manufactured or stored.

The larvae prefer wheat flour, but do not reject other flour and grain products. When wheat flour is not available, also grains, seeds, dried fruit, almonds, nuts and macaroni are eaten by flour moth larvae.

Brown brown flour moth and larva

Brown brown flour moth and larva

The damage is not limited to that which the larvae directly eat. Flour with moth larvae is stained gray-brown by the excrement and will get an unpleasant smell and lumps. In mills where the Mediterranean flour moths are found in large numbers, hoppers and strainers of fibre clog, so you constantly have to stop and clean it out. To avoid this, as well as complaints from customers, some mills are regularly gassed against flour moths. The adult moths do not take nourishment. In daytime they sit quietly, preferably in dark places. After mating, which can last for up to 15 hours, the female lays about 200 eggs within a few weeks. At 20 ° C the eggs hatch in 11 days but at 30 ° C it only takes 3 days until the tiny, 1 – 1.5 mm long, flour moth larvae come out of the eggs. At 17 ° C the larval stages altogether last four months and the pupal phase lasts 16 days. At 30 ° C development speed is increased. Larval development lasts a month and the pupal stage one week. In unheated rooms the larvae hibernate in the winter. In places that are heated in winter, at least four generations can develop per year, and you will find moths and larvae of all ages.

Goat moth

Goat moth

Goat moth

( Latin: Cossus cossus )

From time to time one finds remarkably large circular holes in timber, particularly if there are willows or poplars in the vicinity. These holes are always in the surface timber of structures such as doors and window frames, and they are made by goat moth larvae. The female lays her eggs in crevices of the bark of various deciduous trees, particularly willow and poplar, but sometimes also in fruit trees. The larvae live and feed in the wood for 2-3 years and when fully grown they sometimes leave the tree they have been living in and seek a suitable place for pupation. This usually happens in the autumn when the larvae may be up to 10 cm long, and they may choose any soft timber to provide them with protection. They metamorphose into moths in the following summer.

Common clothes moth

Common clothes moth

Common clothes moth

( Latin: Tineola bisselliella)

This small moth, now common in human habitations in temperate countries, came originally from warmer parts of the world. It was probably not very abundant until houses started to be warmed more or less efficiently. It does not, therefore, live outside in temperate regions, and it is not one of the insects that fly in through an open window.

A female clothes moth lays about 100 eggs, which are difficult to see as they are very small and whitish, and they are usually deposited in the folds of clothing or in among the hairs of carpets and furs. After a few days the eggs hatch and each larva immediately starts to spin a fine tube around itself as a protection against desiccation. The tube becomes covered with gnawed scraps of the material that the larva is living in, together with faeces.

It is worth noting that the faeces which are the same colour as the food and more or less spherical are often mistaken for the moth’s eggs.

The development from the egg to the adult moth may take anything from one month to over a year, depending upon the temperature, the humidity and the quality of the food. The optimum temperature is around 25° C. In a centrally heated house one can therefore reckon on 4 generations in the year. The larvae require a supplement of food other than keratin. They search for spots and stains on the material and will also feed on flour, meat and dead insects.

Clothes moths have been decreasing in number since the 1950’s. This is due to several factors, including the use of effective impregnating materials, an increase in the use of synthetic materials which are not eaten by the moths; vacuum cleaners and the drier climate in our houses also help to keep the moths down.

Small moths

Many of the smaller moths are superficially very similar in appearance. Some attack textiles, some are pests of agricultural crops, while others infest foods (p. 63). In everyday life, however, the moths most commonly encountered are those that attack clothing, and these must have been a nuisance to man for a very long time. As soon as our ancestors started to store skins the moths must have arrived immediately and exploited this new and rich source of food. Evidence that moths have been one of man’s pests over a long period can be found in several places in the Bible. Thus, in Job XIII, 28: ‘And he, as a rotten thing, consumeth, as a garment that is moth eaten.’ Also in the Sermon on the Mount, Jesus says ‘Lay not up for yourselves treasures upon earth, where moth and rust doth corrupt’ (Matthew VI, 19).