Meal moth - Control in practice

We recommend flour moth traps for the prevention and control of mealybugs:

Facts about flour moths

Occurrence: Meal moth (Ephestia kuehniella) are not very common in Danish homes. They are most commonly found in bakeries and other places where large amounts of flour and grain products are found. If you've found moths in the food in your kitchen, it's likely to be two-colored seed moth.

Food: Flour moths are food moths that prefer to lay their eggs in flour so that their larvae can feed on the flour. The caterpillars are the real pests as they are the only ones that feed on the flour and contaminate it with their feces and webs. The larvae can also feed on many other dry foods such as cereals, grains, breakfast cereals, etc.

CombatControl is all about removing all eggs, larvae and adult moths. In practice, when flour moths are found in private homes, it is often a limited number of larvae in a bag of flour or cereal. In these cases, you should discard the food, empty the cupboard where the food was stored and vacuum it thoroughly. Read more about control below.

 

Combat

Controlling meal moths is all about removing all eggs, larvae and adult moths.

InspectionThe eggs and larvae are found in dry foods in the kitchen - especially flour - so inspect all these foods thoroughly. If there is any evidence of the moths' presence, discard the food and remove the waste from the home immediately.

Cleaning & MaintenanceYou should also clean all kitchen cabinets where dry food is stored. Never use water for cleaning as this can make the problem worse, as moisture improves the living conditions for flour moths (and other moths). Instead, use a vacuum cleaner and a dry cloth dampened with ordinary vinegar and do the following:

1. Vacuum all kitchen cabinets and adjacent areas thoroughly - take special care in corners, crevices, cracks, holes, etc.
2. Wipe all surfaces, corners, edges and edges with the vinegar cloth

OriginFlour moths in private homes often originate from grain stores, mills, bakeries, etc. and it is worth investigating where the moths come from. In other words, the moths are brought into the home via food that has been in contact with a population of flour moths at some point in the past.

Persistent problems: In the case of heavy or recurring moth infestations, you should investigate whether flour moths are developing in your home. This is done by inspecting different parts of the kitchen, starting with the kitchen cabinets where the infested food was stored. If possible, move the cabinet or dismantle it. The same should be done with other elements of the kitchen (such as white goods, hoods, etc.) where you suspect the moths may have hidden their eggs and larvae. If eggs and larvae are found, clean them in the same way as described above (i.e. vacuuming and wiping). In addition, we always recommend that you use flour moth traps for the prevention and control of mealybugs:

 

Prevention

You can avoid future flour moth infestations by doing the following:

• Store all dry foods in completely sealed containers
• Regularly clean kitchen cabinets thoroughly without the use of water
• Keep kitchen cabinets organized and sort food often
• Discard all foods with expired expiration dates
• Only buy small amounts of dried food at a time
• Bridge flour moth traps

Note that proper food storage is a very important part of moth infestation prevention, as restricting moths' access to food significantly reduces their ability to reproduce.

Again, keep in mind that flour moths very often originate from a store or another stage in the distribution or production of food and that you should try to tackle the problem there.

 

Flour moths or bicolored seed moths?

The flour moth is similar in many ways two-colored seed mothThis is because they develop in the same way, live in the same places and cause the same damage. In private homes, however, the two-colored moths are far more common than the flour moths. The easiest way to tell the difference between the two species of adult moths is to look at the pictures below:

 

Signs of infestation

When flour moths are detected in flour or other dry goods, they are usually single larvae and any excrement and webs. Foods such as flour, grains, seeds, etc. become lumpy, smelly and discolored (often grey-brown) due to the larvae's webs and excrement.

On dried fruits (such as figs, apricots, etc.), the larvae are typically found in the natural folds and wrinkles of the fruit, or where the fruits touch each other. The fruits often also have holes where the caterpillars have gnawed into. All of this also applies to nuts.

 

Disposal of food

If the damage to the food is minimal, you can choose to freeze it at -18 degrees for at least 2 days or heat it to 60 degrees for at least 1 hour.

Of course, you can also simply discard them. In this case, remember to throw the waste bag into the waste container immediately.

 

Description of the flour mills

Adult meal mothsAdult meal moths are 1.0 - 1.4 cm long and have a wingspan of 1.6 - 2.7 cm. They have long light gray or brownish gray forewings with dark patterns (often "bands" or zigzag patterns) or spots. However, the wing patterns can be blurred or indistinct. The hindwings are whitish gray. The head and body are gray. Flour moths tend to stay in the shade and preferably in the warmest areas they can find. In practice, they often sit on the ceiling.

LarvaeMeal moth caterpillars have white-yellowish or slightly pinkish bodies with black spots, which are used to spin their pupae. Their heads are reddish-brown in color. The caterpillars are very small at hatching and grow up to 12 mm as adults. When a caterpillar begins to spin its pupa, its body becomes a more reddish-brown color.

Eggs: Meal moth eggs are oval, but sometimes have a small white-grey projection at one end. The eggs are very small (0.57 x 0.30 mm) and barely visible to the naked eye.

Flour moth caterpillars have black spots on their bodies that are used to spin their pupae

 

The life cycle of the flour moth

• Adult meal moths: Female moths can only mate once, while male moths can mate 5-6 times in their lifetime. The lifespan of adult moths varies greatly and they can live for about 20 days if they don't find a mate and even longer at lower temperatures (10 - 18°C) if they have access to sufficient food and moisture. The adult moths can consume moisture, fruit juices and the like, but generally do not feed.

• Eggs: Female moths are stimulated by flour and other dust materials such as pollen and talcum powder. The female moth can collect piles of these materials in crevices, cracks, holes, etc. (e.g. in a kitchen cupboard) and lay her eggs in them. Females lay 116 - 678 in their lifetime (average 200) and 75% of them are laid within 48 hours of stimulation. The final offspring is between 50 and 500 individuals and depends, among other things, on the health of the parents at the time of mating and what lighting conditions the males live under. The larvae can only develop at temperatures between 8°C and 32°C (at higher or lower temperatures their development stops completely). They hatch after 4 - 14 days. Read more about moth eggs here.

• Larvae: The larvae feed on the food source they hatch on. This is often flour, but can also be other cereals and even other things such as nuts, dried fruit, mushrooms, peat, rotten wood and more. The larva is shady and is usually hidden in the food it hatches in. When fully grown, it will move towards the surface of the food and then towards a crack, crevice, hole, corner, etc. to pupate. Read more about moth larvae here.

• DollOnce the caterpillar has found a suitable location, it spins its pupa and remains there until it is fully grown. The pupal stage usually lasts 17-20 days, but can last several months at low temperatures. If temperatures get low enough, the pupated caterpillar goes into hibernation. When the pupal stage ends, the adult moth emerges from its pupa and mates immediately afterwards.

The total duration of the flour moth's life cycle can be anywhere from 30 days to around 300 days depending on temperatures and food availability. You can read more about moth life cycle here.