The Spring and Summer months are a good time to be on the look-out for Harlequin Bug in the orchard and applying management strategies to reduce their numbers. Harlequin bug Dindymus versicolor (Herrich-Schaeffer) is a native Australian plant bug in the family Pyrrhocoridae.
The adult bug is about 12mm in length and is very conspicuous. The head and inner margins and tips of the forewings are black; the thorax and base of the forewings are reddish-orange. The underside of the body is tinged with yellow or green and bears some red and black markings.
Harlequin bug is a sap sucker which uses a proboscis (needle like mouthpart) to pierce the epidermis of the host plant tissue. In apples this feeding damage occurs on the fruit and results in slight depressions on the skin of the apple and is associated with a browning of the underlying flesh. Damage on apples typically occurs from mid-summer through to harvest.
As there are no chemicals registered for Harlequin bug control, management is focussed on weed control and cultural methods. These include control or removal of known host weed species including Marshmallow (Malva spp.), Docks (Rumex spp.) and Wireweed (Polygonum aviculare). It’s a good strategy to control host weeds early in their development as some species can be difficult to manage with herbicides as they mature.
Removal of sheltering sites such as timber stacks, piles of branches or removed trees, and other trash from within the orchard surrounds should also help reduce bug numbers in the orchard.
For more information, refer to the NSW DPI primefact entitled “Harlequin Bug in apple orchards”.
Article reviewed by David Williams (Agriculture Victoria) and Alison Mathews (Department of Primary Industries and Regional Development, Western Australia)