Chafer Grubs

Causal organism:

Garden chafer (Phyllopertha horticola)
Summer chafer (Amphimallon solstitiale)
Cock chafer (Melolontha melolontha)
Welsh chafer (Hoplia philanthus)

 

Problem	Chafer Grubs
Host grass types	All turf types
Symptoms	Patches of dead and dying grass coupled with yellowing of the turf especially during dry periods. Most turf damage is caused by other creatures that feed on the grubs. Moles, badgers and birds are the main predators. A badger can do severe damage to any area that is infested with the grubs.

 

Development of the pest

• Adult chafers are medium-sized, reddish-brown beetles about 13–15 mm long.
• The adult chafer will lay its eggs around June–July where they hatch and start feeding on the roots of the grass from July to late September.
• From November onward they burrow deep into the ground and lie dormant under the soil before moving to the surface in the spring when they emerge as beetles.
• Damage is most evident in August and September (grub stage).
• Early symptoms include gradual thinning, yellowing, and weakening of the grass followed by scattered, irregular dead patches.

 

Management strategy to reduce the likelihood of attack

• Keep a look out for grub activity in August–September.
• Monitor the turf in the fall for increased bird activity and secondary damage.
• Use biological nematode treatment to control the grubs when they are young and close to the soil surface.

 

Preventive strategy (guidance only)