Latin: Adalia bipunctata, Coccinella septumtata, i.a.
Ladybugs are always a happy sight for children and childish souls, but if there are too many of them in one place, they may cause problems. Ladybugs is a beneficial animal as they eat aphids during the summer, but in the winter, they prefer to reside in homes, where they can cause problems for humans.
Appearance
Ladybugs are known for their beautiful red color, but in fact ladybugs can vary greatly depending on the species. The two most common species in Denmark are Adalia bipunctatata, which is known as the two-spotted ladybug, and Coccinella septumtata, which is known as the seven-spotted ladybug. These are both red, but the two-spotted has only two black spots, while the seven-spotted has seven spots; very logical.
In addition, there is the non-native ladybug, which was observed in Denmark in 2006 for the first time. It is called the Harmonia Axyridis, also known as the harlequin ladybug. The harlequin ladybug can vary greatly in appearance. The coverts can be anything from dark red to yellowish orange, and there are not a fixed number of spots that it can have, but there are always in between 0-19 in total. However, there is also another type of harlequin ladybug, which has completely black coverts with red spots.
This large variation is the reason why it can be difficult at first glance to find out which ladybug you are looking at. Whether it is an invasive or a native species. A good indicator is the size. The Harlequin ladybug tends to be larger than the native species of ladybugs.
Biology and behavior
Ladybugs are a kind of beetle. Therefore, like all other beetles, they go through the common beetle stages, egg, larva, and pupa to a beetle. During spring, the adult ladybug lays its eggs close to a food source. This food source is often a colony of aphids. The eggs hatch in just 3-5 days, where the larva will nourish on the aphids over the next few weeks, after which it pupates. The pupa sticks to the surface and is completely immobile. A few days later, the adult ladybug emerges from the pupa. In Denmark, there are at least two generations of ladybugs per. year.
Nearly all species of ladybugs feed on aphids during the warmer months. But they can also be found in fruits when the weather starts to get colder.
The Harlequin ladybug is more aggressive than its native cousins, which can lead to biodiversity problems. If the harlequin ladybug eats too much of the food that the two-spotted and seven-spotted ladybird should eat, we may risk losing our native ladybug to this more aggressive species.
Damage
Beside the worries that the presence of the harlequin ladybug may cause in the danish nature, it is also an invasive species. In late summer and autumn, ladybugs seek towards heat, and as humans we heat our homes. Therefore, you may risk that they more or less invade your home, which to many people will be quit annoying.
Another problem, beside the overwhelming quantity of ladybugs, could be, that they will search for fruit, which can damage various products. Ladybugs are difficult to get out of the fruit and they leave a bitter and bad taste, potentially they can ruin an entire harvest.
Prevention and control
As a starting point you do not need to prevent ladybugs, as they do not pose a danger inside. They do not reproduce indoors, and they do not transmit diseases to neither humas nor other animals. Nor do they cause any damage to the home itself.
Of course, they can still be a nuisance if there is an actual invasion of ladybugs. If you observe many ladybugs in your home, they can typically be removed with a vacuum cleaner. However, one can also just wait until winter ends, as the ladybugs then will seek outside again.
"Pests in House and Home"
"Bed Bugs - Bites, Stings and Itches"
"Food Pests"
"Husets dyreliv" (Insects Around the House - Only danish)
"Skadedyr i træ" (Timber Pests - Only danish)
"Stuefluen" (Common Housefly - Only danish)