The Content Of The Article:
- How do the mealworms get into the flour?
Especially in starchy, dry foods such as flour and other cereal products nestles the meal beetle. The warm and dark environment appeals to the pest, also he finds here food in excess. Immediately dispose of stocks of flour beetles and search your premises for other hidden animals. You can use pheromone traps that attract mating adult beetles.
Scientific name: Tenebrio molitor
Family: Black beetle (Tenebrionidae)
Common names: mealworm
Appearance of the adult animal: elongated, flat, black-colored body; Underside, limbs and antennae reddish brown; Grooved wing surface
Length of the adult animal: 10 to 18 millimeters
Appearance of the larva: yellowish brown, with eye-catching darker rings, between 20 and 25 millimeters long
Occurrence: worldwide; preferred dark and warm places: pantries and other places with flour and cereal products, also inof the great outdoors (pigeons and other birds' nests, deadwood)
Food: mainly starchy food, often flour and other cereal products
Development: complete metamorphosis
Harmful effect: Food damage, carriers of pathogens (bacteria, but also dwarf tapeworm)
fighting: in private households immediate removal of infested supplies
Use: Larvae as food worms for pets (birds, reptiles, amphibians or fish), in Switzerland since May 2017 as food also approved for humans
The nocturnal meal beetle reproduces sexually, with little difference between female and male animals. The mating takes place at the beginning of the summer. Subsequently, the female lays between 200 to 300 eggs - preferably in warm and dark places such as in pantries with open flour and other cereal products. The tiny, white and sticky eggs are not visible to the naked eye in flour or oatmeal. However, if you bake the flour together strangely or stick the oatmeal together, then you can expect an infestation.
Growth and developmentThe larvae of the flour beetle, which hatch from the tiny eggs, are also called mealworms, although from a scientific point of view they are not worms. They are only two millimeters long after hatching, but grow very quickly to an average length of 20 to 25 millimeters. They shed several times and over time assume a yellowish-brown color with darker rings. The animals feed on the surrounding food and pupate themselves in it. Freshly hatched adult beetles are initially very light colored, but darken within a few hours. The entire life cycle takes place within three to four months, after which the beetle dies. Several generations of the flour beetle can develop each year.
harmful effectAn infestation with flour beetles is often not noticed until it is well advanced. First and foremost, the harmful effect in private households is that all infested food must be disposed of immediately - not in the household waste, but in the garbage can. Otherwise, the larvae in the garbage just continue to evolve and pupate there, with the result that a renewed infestation can not be stopped. In addition, the meal bug can transmit diseases if you consume contaminated food. For example, the pest is considered a carrier of the dwarf tapeworm (Hymenolepis nana), which can be up to six inches long and nestles primarily in the intestine of children and people with a weak immune system.
How do the mealworms get into the flour?There are several ways in which the meal beetle gets into the flour (or other supplies). Probably the most common transmission variant, you get the pest by already contaminated with eggs or larvae food in the house. An infestation already took place in the mill or during the manufacturing process, which the manufacturer did not notice. Subsequently, the flour beetles multiply rapidly in the private household and infest other supplies. However, this is not the only way to get flour beetles into the house. You get u. a. also like this:
- from pigeon or bird nests under the gutter
- from the garden (piled up deadwood, mulch material, compost)
- escaped animals from breeding, such as for terrarium animals
Tip: The nocturnal meal beetles are attracted by light.Close the windows as soon as you turn on the lights or install mosquito nets in front of the windows and terrace or balcony doors.
In private households, the most important control method is to carefully search all stocks for signs of infestation and to dispose of contaminated food immediately. A clear indication of eggs deposited in flour, cereal flakes or the like is that they suddenly bake together and sometimes even threads are visible. The larvae can often be discovered while sifting.
In addition, in order to actually catch all meal-beetles and thus to prevent a renewed attack in the same way, you should not only dispose of your supplies. The animals also like to hide in cracks and joints, small caves and behind cabinets. Suck off all the regions in question - all cracks, etc. - and move the cabinets to clean them from the back. Do not forget to check the cabinets!
Tip: Repeat this procedure every four to six weeks, as you will not catch all the beetles and their offspring at once.
If you want to be on the safe side and are more likely to avoid re-infestation from the outset, you should also try these measures:
1. Setting up pheromone trapsPheromones are sex attractants that are only perceived by adult animals. The classical pheromone traps contain an attractant for male meal beetles and serve less targeted control than the detection of pest infestation. Set up several of these traps and wait a few days: mating male animals will stick to the sticky surfaces so they can discard them along with the traps. If it concerns only individual animals, these may come from the garden and there is (still!) No infestation. However, if the findings accumulate, it is best to look for the source and take appropriate action.
Tip: Pheromone traps are not suitable for controlling meal beetles, as they only catch the male animals. However, such a trap can help you realistically assess the extent of infestation. In addition, the trapped males are no longer able to fertilize existing females, so that the population is limited according to the catch quota.
2. Setting up UV light trapsEven so-called UV light traps are used to catch adult meal beetles. In this case, however, both male and female animals of the trap are literally "on the hook". Light traps are designed to attract the nocturnal beetles and eventually adhere to the integrated adhesive surface. The adhesive surface together with the captured beetles can be disposed of, the lamp itself can be used on average up to 9000 hours. Again, you should not use the trap as a sole control measure, because it attracts only the adult animals. The hidden larvae and pupae, however, remain hidden and can develop undisturbed.
3. Application of non-toxic insecticidesIn agriculture and in industry (for example in grain mills or bakeries), packaged cereals or cereal products are fumigated with nitrogen, carbon dioxide or hydrogen phosphide to combat or prevent the meal beetle. In a proven infestation come in such systems also thermal processes are used, in which all stages of development of the flour beetle at temperatures of 60° C and more are killed. In private households, of course, such methods are not feasible. But even here you can resort to non-toxic contact insecticides, for example on the basis of silica, neem or tea tree oil or pyrethrum.
The latter is an extract of the flowers of various chrysanthemum species, which has been used successfully for centuries for pest control. The above-mentioned preparations are especially useful for the treatment of hard to reach areas.
Tip: Never resort to insecticides that are not specifically approved for use in homes - especially if you want to use them in the kitchen. The poison not only kills the mealworm, it also penetrates your food.
4. Thermal methodsIn order to avoid the development of flour beetles from the larvae and pupae found in the stocks, you should put the food in the freezer compartment of your refrigerator for some time before disposal. Frost kills both adult and juvenile animals just as reliably as temperatures above 60° C.
preventionBy means of targeted preventive measures, a meal of beetle infestation can be well prevented right from the start. The following hints are useful for this:
- Do not store dry supplies such as flour, oatmeal, cereals, etc. for long
- instead consume quickly
- and buy fresh more often
- Close reservoir tightly
- Never store supplies open (eg leave flour in bags)
- Thoroughly check newly purchased supplies before they are cleared
- set up pheromone traps for control from early summer
- Quickly remove pigeons and other bird nests on and in the house
- Check longer stored supplies regularly
Tip: Check your kitchen cabinets regularly, if there is not a forgotten flour bag in the far corner.