Oulema cf. melanopus Linnaeus, 1758
Common names: Cereal Leaf Beetle [En], Criocère de l'orge, Criocère des céréales, Léma à pieds noirs [Fr], Grasgoudhaantje [Nl]
Meise, BRABANT ● Belgium
Description: Adult beetles are relatively distinct in appearance with metallic bluish-black elytra, and body parts except the pronotum, femora and tibia which are red to red-orange. Antennae are greater in length than half the body and antennal segments 7 and 11 are about twice as long as wide while segments 8-10 are less than twice as long as wide. Length of the adult stage ranges from 4.6 to 5.3 mm, with the female being larger.
Biology: Oulema melanopus typically have one generation per year, but occasionally two years are necessary to complete development of a single generation in more northern climates. Adult beetles overwinter in protected areas such as wind rows, crop stubble, tree bark crevices, etc, and start to become active when daily temperatures rise above 9-10 C.
Following emergence, beetles feed, mate and lay eggs for approximately six weeks. Eggs are adhered singly or in groups of two-three on the leaf midrib and 100-400 eggs are laid per female. Larvae emerge from the egg and feed on the upper leaf surface without fully perforating the lower leaf surface. Larvae have the interesting habit of covering their body with fecal matter which is thought to protect the larvae from desiccation and predation. Larvae pass through four larval instars before leaving the plant to pupate in earthen cells 1.25 to 5 cm deep. Adults emerge shortly after (15-20 d) and begin to feed on available crops or wild hosts. Adult feeding is characterized as between vein and completely perforating the leaf tissue.
Oulema melanopus feeds on all cereals; barley (Hordeum spp.), wheat (Triticum spp.), oats (Avenea spp.) rye (Secale spp.), corn (Zea mays) and wild grasses.
CPC, 2003.Pest Assessment, Cereal Leaf Beetle, Oulema melanopus (L.), (Coleoptera: Chrysomelidae)