The two-spot ladybird, Adalia bipunctata, is a species of small, flying beetle that is found in northern Europe and other parts of the world. The wings of these beetles are covered by two tough structures known as elytra, as shown in Fig. 2.1. protective elytra [Figure 2.1] A. bipunctata is an important predator of insect pests such as aphids. These insect pests feed on plants, including many crop species. Population numbers of A. bipunctata fluctuate in response to changes in the population numbers of their prey. The elytra of A. bipunctata show phenotypic variation. The three most common morphs (forms) found in northern Europe are known as typica (T), quadrimaculata (Q) and sexpustulata (S). • The typica morph, shown in Fig. 2.1, is mostly red with two black spots and is described as non-melanic. • The other two morphs are described as melanic as they are mainly black with some red. • The distribution of the colours in these three morphs is shown in Fig. 2.2. non-melanic melanic typica (T) red black black red quadrimaculata (Q) sexpustulata (S) [Figure 2.2] In northern Europe, the populations of A. bipunctata hibernate (are inactive) during the winter. As the temperature increases in early spring, the populations become active. The populations remain active and produce three generations before the next winter begins.