Latin: Necrobia
The ham beetle is an international beetle. This means that you can find species of the Necrobia beetle genus all over the world, so you can of course also come across them in Denmark. In Denmark, we have three different species of ham beetles, two of which can be a nuisance.
As pests, the ham beetles eat lots of different foods, but they can also prey on other insects. For humans, however, ham beetles are most annoying when they show up at a warehouse or in a store as they eat their way through the inventory.
Appearance
The three ham beetles that you can encounter in Denmark are fortunately easy to recognize, and you can also easily see the difference between the three kinds. Overall, the ham beetle is 4-6 millimeters long when fully developed. Like other insects, the ham beetle has six legs. Ham beetles have long hind bodies, while they are shorter in front. You can see the difference between the three different species in Denmark in their color.
The first is a red-legged ham beetle, also called Necrobia rufipes. The red-legged ham beetle naturally has red legs, while its body is a dark and metallic blue. The next is called the red-necked ham beetle, i.e., Necrobia ruficollis. This one also has a body that is dark and metallic blue, but it is red on the chest (which can also be seen on the “back” of the beetle). This reddish color is also found on the front of the ham beetle’s cover wings.
Finally, we have the blue ham beetle, also called Necrobia violocea. The blue ham beetle has a full-colored, uniform bluish tone, and this beetle is the only one that is apparently not a pest. So, you can guess the danger by looking at the color. All three species of ham beetles can fly when fully grown.
The larvae are significantly larger than the fully grown beetle, and they can grow up to 10 millimeters long. The larvae can be recognized by their greyish white color. On the upper side they have clear, violet drawings. In addition, they have two darker hooks on the rear end.
Biology and behavior
Adult ham beetles like to eat carrion, and they can typically get a lot of nutrition out of the driest parts of a carcass. Museums and similar institutions must keep a particularly close eye on ham beetles, which have also been found in Egyptian mummies. However, the ham beetle is not picky. It likes to eat dried food, such as copra, cheese, smoked products, figs, dried fish, and cocoa beans. There is also a risk of finding ham beetles in stored fishmeal, medicinal products and in powdered eggs and milk.
When they are not eating carrion or dried food, they like to prey on other insects. Both ham beetles and ham beetle larvae like to eat smaller insects. However, the larvae are the hungriest, and therefore eat significantly more than ham beetles.
Damage
Although, as mentioned, there are three different species of Necrobia in Denmark, there are only two of them that can be a nuisance. The red-legged ham beetle (Necrobia rufipes) and the red-necked ham beetle (Necrobia ruficollis) go into different foods, which makes them pests for many industries. As mentioned, they can also be dangerous to have near certain museum objects, although this is of course not a problem for most of the people Denmark.
It should also be noted that some ham beetle larvae like to dig holes in woodwork and similar materials if they cannot find a crack to pupate in.
Prevention and pest control
Ham beetles simply cannot survive at temperatures below 9 degrees. If you are afraid of finding ham beetles or ham beetle larvae in your stock, a cool storage can do wonders. However, the beetles will begin to reproduce, pupate, and generally live again when the temperature rises, so this solution will not work if you have already found ham beetles in your stock. To prevent ham beetles, you can freeze your food to below -18 degrees. At this temperature, all stages of ham beetles die if the goods are kept frozen for about 7 days. Heating the goods to 60 degrees for at least one hour can also work.
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"Bed Bugs - Bites, Stings and Itches"
"Food Pests"
"Husets dyreliv" (Insects Around the House - Only danish)
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