Six-spotted mite, Eotetranychus sexmaculatus (Riley), is native to the Americas and was first recorded in Western Australia in 1986 on avocado seedlings from eastern Australia.
In the same year and presumably from the same source, the mite was recorded for the first time on avocados in New South Wales, Queensland and South Australia. It also occurs in New Zealand.
The mite feeds primarily on the lower surface of leaves, concentrating its activity adjacent to leaf veins. During feeding, the mites penetrate leaves with their stylets and suck out the cell contents. This results in discolouration and death of leaf tissue.
Signs of feeding on white and red grape varieties are yellow or red shadows respectively, on either side of the veins and visible from both sides of leaves.
On avocado, six-spotted mite feeding appears as purple discolouration next to leaf veins.
In citrus, primarily grapefruit but also oranges, feeding on the leaf stems and occasionally the fruit stems will cause the fruit to yellow and fall. Six-spotted mite on citrus has not been recorded in Western Australia.
Kiwifruit is also a host for six-spotted mite, but this has not been observed in Western Australia.
Heavy infestations result in severe defoliation. This results in delayed ripening or failure of grapes to ripen and reduced quality and yield of fruit.
Avocados are particularly susceptible to the mite and low numbers can defoliate trees, exposing fruit to sunburn.
Awareness of whether the mite is present is the first step in minimising its potential for damage.