Pantry moth: detection, treatment & prevention
Here you can learn everything about pantry or kitchen moths. Use of beneficial organisms and household remedies (such as vinegar) is also discussed.
How to detect a pantry moth infestation?
The term pantry or kitchen moth is an umbrella term for several pests that are different species but look relatively the same. Pantry moths include the Indian-meal moth (Plodia Interpunctella), the Mediterranean flour moth (Ephestia kuehniella) and the cacao moth (Ephestia elutella). However, to prevent and successfully treat a pantry moth infestation, it is not necessary to differentiate between the individual moth species. So, why do infestations occur anyway? They are caused by food contamination in stores and the trade or by adult moths that find their way into kitchens to lay their eggs. It is important to note, that in both cases you might not even notice the adult moths. The adult individuals do not cause any damage themselves. The main culprits are the larvae of these moths.
If food such as cereals, flour, nuts, chocolate or tea is stored incorrectly, the larvae can quickly find access to it and make the food inedible. The inedibility of the food is not caused by the larvae themselves as they are non-toxic. It is the excrements and the webs, that the larvae are responsible for, that destroy the food. By the way, the best way to recognise an infestation by food moths is to look for the webs. If, for example, some cereal grains hang from the packaging as if by magic, or if lumps form in the flour or cereal, this is a sure sign of existing webs.
Unfortunately, the webs and the larvae excrement further worsen the contamination of the food. It is likely, that the contamination will attract fungi and mites. Among the fungi, mould can also be present, and in that case, the rest of the food should go straight into garbage. What is more, the larvae can be observed in the food, too. After hatching, the larvae are too small to be visible to the human eye. However, the larvae develop quickly and reach the lengths of up to 1.7 cm. The larvae of the pantry moths are rather unsightly and are reminiscent of maggots.
Pantry moths: a profile
There are several types of pantry moths and they all vary slightly, but all of them can be distinguished well from the notorious clothing moth. The clothing moths are yellow and silver in colour and have neither patterns nor stains on their backs and wings. The kitchen moths, on the other hand, always have patterns and brown stains on their wings. If there is still some uncertainty, have a look at the pictures below. The larvae of the pantry moths reach the size between 1.1 and 1.7 cm. When the larvae grow fully, they leave their source of food and move elsewhere, sometimes covering quite impressive distances.
The larvae find a dark and dry place and then pupation follows. The adult moths (0,4 – 14 cm in size) are responsible for the new generation. Depending on the type of pantry moths, between 50 and 400 eggs can be laid. Therefore, even a single moth female can wreak havoc in a kitchen. The butterflies belonging to the pyralid moths’ family (Pyralidae) need a total of 30 – 380 days for their complete development. In warm temperatures the insects develop much faster, while in cold temperatures the development can be delayed considerably. In some cases, development can be stopped completely if it is chilly enough. This is because the Indian-meal moth and the flour moth are adapted to warmer regions such as the Mediterranean.
Preventing a pantry moth infestation
The most common cause of an infestation is food that remains in its original packaging. Plastic, paper or cardboard packaging are no obstacle for the pests. The larvae simply chew a small hole to create an entrance to get to the food. Therefore, it is better to switch to airtight glass, ceramic or thick plastic containers. This is the only way to keep the voracious larvae away. Even if the food packaging seems to be tightly closed and appears to be sealed well, it does not guarantee complete protection.
But even the best storage containers won’t help if the pests are already present in the food while shopping. Fortunately, this happens very rarely. If the problems with pantry moths persist or happen frequently, setting up a trap is worthwhile, as it can help detect the infestation before it aggravates. The pheromone traps contain an irresistible pheromone that attracts the male moths. The moths then fly to the trap and stick to it. In this way, it is easy to quickly identify that an infestation is happening. However, we would like to point out, that only one infestation can be detected using the pheromone traps. The pheromone traps are not a method of control; they only help with recognising the outbreak, so that it can be treated with other methods afterwards. It is also worth storing foods that are likely to fall victim to the pantry moths as cool as possible. In cooler places the moths cannot develop well.
Treating a pantry moth infestation
If an infestation has been discovered, all food should first be checked for larvae and webs. Contaminated food should always be disposed of as soon as possible. However, the larvae can continue their development even in the domestic waste, so it is important to kill them beforehand. This is best done in a freezer. There, the food must be frozen for three days and only then it can be disposed of as household waste.
Another problem is the eggs of the moths. Since they are basically invisible to the human eye due to their size, the shelves and pantries must be thoroughly cleaned with a vinegar-water mixture after you detect the infestation. The moth eggs are destroyed by the vinegar solution. If you are dealing with a severe infestation, it might be helpful to consider beneficial insects. For example, the ichneumon wasps (Trichogramma Evanescens or Habrobracon hebetor) can be used to treat the outbreak. If it is impossible to pinpoint the exact location of the pest, the Habrobracon hebetor ichneumon wasp will detect the moths and their caterpillars with certainty even in larger spaces.
When using beneficial insects, it is important to provide the perfect conditions so that the treatment is effective. The right temperature is one thing to keep in mind, for example. In addition, it is important to remain patient and give the beneficial insects enough time to find and eliminate all of the pantry moth larvae. If all of the recommendations are followed, the tiny ichneumon wasps will get rid of all the pantry moths. Moreover, the wasps are barely noticeable and after they are done, they will disappear. Of course, insect sprays could also help, but we strongly advise against it. Using sprays closely to food and in domestic spaces is not recommended. In our opinion, the natural way of control with ichneumon wasps is definitely the better alternative.