more. The last larval stage is approximately the size of an adult beetle. Once it has eaten enough, the larva attaches itself to a substrate and moults into a pupa. Inside the pupa, the adult develops. Finally the adult ecloses from the pupa. Sex ratio anomalies Symbiosis In some populations, the majority of the beetles are female. In these populations, 80-90% of the offspring are female. The cause of this anomaly is the presence of symbiotic bacteria living within the gametic cells of the female lady beetles. The bacterium is too large to live in the male gametes (sperm), so the bacterium can be transmitted to the next generation only through female gametes. When it ends up in a male, it will die when the male dies. Therefore, it kills most of the male embryos in the newly laid eggs. These dead embryos then serve as food for their sisters when they emerge from their eggs. This trait is associated with a variety of bacteria (Wolbachia, Rickettsia, and Spiroplasma) which are present in between 0 and 20% of females, depending on locality. Parasitism The two-spot ladybird also carries a sexually transmitted infection in Central and Eastern Europe. The infection is an ectoparasitic mite Coccipolipus hippodamiae that transfers between male and female (and female and male) during copulation. The infection sterilizes female two-spot ladybirds, and at some points of the year, up to 90% of adult two spots become infected. As biological control agent A. bipunctata is used as a localised biological control agent against aphids in, for example, greenhouses.. The two-spotted lady beetle was introduced into Australia specifically as a biological control agent. References External links Biological pest control beetles Insects used as insect pest control agents Beetles of New Zealand Coccinellidae Beetles described in 1758 Taxa named by Carl Linnaeus National symbols of Latvia