Soapberry Bugs

December 2009

Is your garden bugged?

These insects have been all over my plants for weeks. Are they a pest?

Answer

The insects in your photo are Soapberry Bugs, Leptocoris sp. These bugs belong to the Family Rhopalidae and there are 5 Australian species in the genus Leptocoris.

Soapberry Bugs are often found in clusters containing different stages: winged adults and wingless nymphs. When not feeding they may shelter in a favoured area (like the underside of this Monstera deliciosa leaf - see first image).

Soapberry bugs do not feed on foliage but on seeds. They are 'true bugs' meaning they possess a sucking tube, called a rostrum, located underneath their heads. There are a number of fine needles in the centre of the rostrum which they use to pierce the seed case and then pump in saliva . The seed is dissolved into a soup which is sucked up through the rostrum.

Soapberry Bug moulting. Soapberry Bugs feeding on seed

They sometimes occur in large numbers in Brisbane because of the abundance of suitable seeds produced by weedy plants such as the introduced Golden Rain Trees, Koelreuteria elegans. They are native insects however and also use native plants in the Sapindaceae family.

Nymphs moult (shed their skins) several times before they develop into fully winged adults. Freshly moulted bugs are soft and pale coloured before their skin hardens. Their red and black colouration serves as a warning to potential predators that they are distasteful and possibly toxic to eat.

Queensland Museum's Find out about... is proudly supported by the Thyne Reid Foundation and the Tim Fairfax Family Foundation.

Related Links