Colorado potato beetle (Leptinotarsa decemlineata) with a potato plant, artwork. This beetle is a serious pest of commercial potato crops. The insect is about 10 mm long and native to the south-west of North America, although now they are also found across North America, Europe and Asia. Females lay eggs (yellow) on the underside of host leaves; after 4-15 days the eggs hatch into larvae (red) which feed on the leaves. The larvae progress through 4 growth stages (instars) before burrowing into the soil and forming a pupa (brown) with a hard protective coating. After a period of several weeks or several months, depending on conditions, the adult insect emerges and returns to the host plant to feed and mate.