Before becoming a ladybird, the beetle must pass 4 stages:
1. The egg, which will hatch after 5 days.
2. The larva, who grows during 10 to 15 days and will moult 3 times.
3. The pupa, who is immobile and will transform in 6 to 8 days.
4. The adult beetle who can lay eggs after 1 to 3 weeks.
In general eggs are laid in clutches in spring or the start of summer. They are mostly slender elliptic in shape and of a bright yellow or orange color. An Adalia bipunctata female can lay 20 to 50 eggs per day during 2 weeks. They can be found on twigs or leaves, infested with aphids.
After hatching the larva eats the egg shell and the non-hatched eggs in its clutch. Afterwards it will start searching for aphids. Its search for aphids is guided by contact and smell and not by sight, because the larva is blind. While moulting it attaches itself and stays immobile for a couple of hours.
When in the pupa stage (1), the most immobile stage, the ladybird is transforming inside the pupal case.
After 6 to 8 days the adult beetle will rip open the pupal hide and crawl out. At first it will be completely yellow. Then it will look for a place to hide to rest and let its wings harden. After a few hours the color and the pattern will appear. In this stage only 20 % of the young beetles survive.
Ladybirds probe their world with their antennae. They seize their prey with their mandibles (2). They can devour up to 90 aphids per day but in the larval stages they are the most voracious: larvae can eat up to 150 aphids per day!
In September/October the adult ladybirds search for a place to hibernate, which can differ depending on the species. Adalia bipunctata likes brick walls, windowsills or small crevices in tree bark, where they “hide out” with tens of their fellow adults. During winter mortality is high. It can depend on the severeness of the winter, whether or not spring is early, availability of food and the presence of parasites. |
