Summer lawn pests
Dead patches in summer lawns are difficult to diagnose but they are often caused by insect pests eating the grass leaves or roots. In warmer coastal areas, the most common leaf eater is the armyworm, a caterpillar that comes in huge numbers and can devour a lawn almost overnight. Put a piece of damp towel or cardboard on the edge of the eaten patch and check beneath it in the morning. Dispose of any sheltering grubs, or treat the area with an organic pesticide.
If birds are pecking at or near dead patches of loose grass, the culprit could be beetle larvae (above), also known as curl grubs, munching on the grass roots. Add some dishwashing detergent and tea-tree oil to a bucket filled with water and pour it over the affected area to drive the grubs to the surface, where the birds can pick them up. Avoid leaving outdoor lights on at night, as these attract the beetles. Nematodes are commercially available for biological control.