What's eating my macadamia?

Macadamia trees in Hawaii and California face damage from macadamia felted coccid (scale), macadamia nut borer, and stink bugs that scar and abort developing nuts. Rats and birds are significant vertebrate pests in Hawaiian orchards. The macadamia felted coccid is the most widespread and consistently damaging insect pest across growing regions.

White cottony masses on stems, leaves, and nut clusters; heavy infestations cause shoot dieback, cluster abortion, and sooty mold from honeydew White oil (horticultural oil) spray targeting crawlers; introduce or conserve natural predators (Coccophagus parasitoids); prune and destroy heavily infested stems

Larvae bore into the developing nut and shell, causing premature drop; exit holes visible on fallen nuts; kernel is partially or fully consumed Collect and destroy premature nut drops promptly; pheromone trap monitoring; spinosad or Bt sprays timed to moth flight peaks; maintain sanitation of fallen material

Piercing damage to developing nuts causes dark gum spots, kernel browning, and nut drop before shell hardens Monitor with pheromone traps; pyrethrin spray at threshold; remove weedy cover crops during high-pressure periods; Trissolcus parasitoid wasps provide biological control

Gnaw nuts off clusters at night, particularly in Hawaiian orchards; can take 20–40% of unharvested crop on trees with canopy connectivity Trunk rat guards (smooth metal bands 45–60 cm wide); remove canopy bridges to neighboring trees; bait stations placed responsibly away from non-target wildlife