Eggs hatch between September and November. The time of hatching depends on plant cover, topography and aspect. The relatively high soil temperatures on the crests of sandy ridges and north-facing slopes cause eggs to develop rapidly and hatch early, but eggs on well-vegetated slopes and flats hatch later because these areas are slower to warm. This creates a mosaic of hatchings which can vary over time from property to property and in some cases within a single property.
Hatching in a district may be extended over several weeks although most eggs in a particular site will hatch within a few days of each other.
The earliest emerging grasshoppers are found under marri trees on sandy ridges to the north of Perth. Other sites for detecting early emergence are around trees where there was bare, sandy ground in the previous summer, particularly on north-facing slopes and where the adults were feeding on summer-green pasture during the previous season.
It is the early, high density, synchronised hatching of grasshoppers (more than 100 per square metre) on the crests of ridges that later causes most damage.