Argentine
Stem Weevil
Common
name: Argentine Stem
Weevil
Scientific
Name: Listronotus bonariensis.
Metamorphosis:
Complete,
there maybe 2 or 3 generations per year.
Adult:
Grey
to grey brown. About 2.5mm in length with an obvious snout. Mandibulate
mouth parts.
Winter-feeding,
spring they mate and lay eggs.
Eggs:
White
yellow colour, oval shaped up to 1mm long.
Laid
singly or in-groups. The eggs develop over three weeks and turn an olive
green in colour.
Larvae:
Creamy
white 2mm in length.
Hatch
out and chew a tunnel in the grass stems. Generally
down to the crown and kill the growing points. Warm temperatures and
rapid feeding they develop from less than 1mm to 6mm in 14 days.
Pupae:
light
brown, 2mm in length.
Pupate
in the soil and take 14 days or so and adults emerge to feed, fly and
lay eggs.
Hosts:
Bents,
Rye, Fescues and Poa spp.
Symptoms:
Yellow mottling of grass dispersed dead yellow patches of turf. The
maggot may be seen in the crown of the plant. Usually starts on the
edges of the green.
Prevention:
Chemical
control
