Peak Activity: February - May
Black Beetle is a major ryegrass pest in the Northern North Island from Taupo to
Kaitaia, where mean air temperatures are above 13°C. Black Beetle enjoy the sandy,
peaty or free draining loam soils of the north.
Black Beetle produce one generation per year, with adult females laying eggs from
late October to late December. Larvae develop during three instar stages over summer
before pupating to adults in February and March. Adults begin emerging in pastures
from late February and actively feed over the autumn months before overwintering
in the soil. While the larvae has an appearance similar to Grass Grub larvae, the
adult Black Beetle is easily distinguished by its classic beetle appearance and
glossy black exterior.
Larvae damage appears similar to Grass Grub feeding. The larvae feed on roots of
established grasses which can lead to the destruction of the root system, pasture
pulling and brown-off. The adults present the main threat to newly sown pastures
with their transition coinciding with the autumn sowdown. The adults chew at the
base of the newly emerged plants to the point where plant death occurs. Adult Black
Beetle are mobile, so all newly sown pastures are a potential target for the pest.
Prevention and Control
- Superstrike Grass seed treatments
- Use of grasses with Endo5, AR37 or MaxP endophytes for long term protection
- Use of a summer forage crop as an alternative feed source for stock
- Use of resistant species e.g. lucerne
- Contact insecticide