Grass Grub Chafer
Phylum: Arthropoda
Subphylum: Uniramia
Class: Insecta
Order: Coleoptera
Family: Scarabaeidae
Subfamily: Melolonthinae
Genus: Costelytra
Scientific Name: Costelytra zealandica
Common name: Grass Grub Chafer, Grass grub beetle
The Grass grub is the natural enemy of the common grass. Native to New Zealand the Grass Grub, ‘Costelytra zealandica’ has proliferated since we became a pastoral country.
June and July are the most active months of the grass grub. Activity starting in March and building up to June/July then dropping off to finish in September. Where the adult beetle emerges in October and is active till December dependant on area and temperatures. he Females mate soon after emerging and lay their eggs back near where they emerged from. (unless distracted by night lights) A female lays about 40 eggs in batches, 70 to 200mm below the soil surface. The larvae hatch in about 20 days dependant on soil temperature. They start feeding at these low depths and over the months work their way up to the top 20-30mm of soil in the May to July period. During the dry soil times of summer the grubs hibernate till the soil becomes moist with autumn rains.
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