Saturday Morning With Jack Tame

Grass grub have always been a “problem” in NZ gardens and lawns. They are c-shaped grubs that live underground, feeding on roots of grasses and other plants/shrubs. There are a number of species in the Beetle Family Scarabeidae (scarab beetles), but the native grass grub, Costelytra zealandica has always been in NZ. It’s traditional habitat and host plants were native grasses, such as tussocks, and they occur at quite high altitudes. There is no doubt that these beetles considered the new, high-nutrient imported grasses as ice-cream, especially when we started planting whole paddocks full of that stuff! Tiny larvae emerge from eggs and slowly grow larger, shedding their skin as they grow. Each growth phase is an “instar”. Larvae creamy coloured and shaped like the letter C.   Their damage pattern is grasses losing roots and becoming stunted and leaves yellowing – in bad situations these plants die en masse. If you can literally roll the dead grass mat up (as if it were a carpet), your problem is likely grass