Adults grow into 12 to 15 mm shiny black beetles. The males have a thickened tarsus on front leg (to help them dig).
The grubs have distinctive orange spiracles along abdomen and thorax. Their raster is a transverse narrow slit (smiling grub).
Relatively inactive during winter
Mate and lay eggs in spring (between 6 -12 eggs per female)
Eggs incubate for generally 2 - 5 weeks dependent on soil temperature
Eggs hatch into 1st instar larvae
Larvae develop through 3 stages
1st instar: feeds on decaying organics matter
2nd instar: As they grow, they begin to feed on plant roots
3rd instar: The larvae are fully grown larvae, about 25mm long
When the larvae are fully grown they build a chamber, then move into pre-pupae and pupae stages
The pupae develop into adults and emerge after about 2 months in late summer and autumn
The plant loses ability to access moisture in the soil effectively due to root damage, giving the appearance of drought like symptoms in irregular patterns.
During severe damage, large patches of turf lose root structure and the turf can actually be peeled back exposing large numbers of feeding larvae.
Highly managed, lush green turf is highly attractive to beetles that search for good food sources
Beetles are sometimes attracted to lights.
Weather patterns can have a large influence on population numbers and significantly increase chances of turf damage
Generally, after two consecutive long dry spring/summers, this is the ideal trigger for plague populations
On many occasions, the biggest turf damage can occur from animals (birds, foxes) digging turf up to feed on larvae
Life cycles seem to have extended over the past years
Control very difficult to achieve once 3rd instar stage is reached
Best control is achieved targeting 1st and 2nd instar stage. Larvae is smaller requiring less chemistry to gain control
ACELEPRYN Turf Insecticide – preventative applications applied in early to mid-October at 750 mL/ha for 3 months control or at full rate for season long control (up to 6 months) at 1.5 L/ha.
MERIDIAN Turf Insecticide – preventative applications applied in early November prior to or at peak egg hatch, at 1.2 kg/ha for up to 3 months control.
SPINNER Turf Insecticide – Apply prior to or at peak egg hatch, late September through to mid October or when small larvae are present at 1 kg/ha. Ensure product placement as close to soil surface as possible.