Horehound bug

The horehound bug, Agonoscelis rutila, suck the sap of the horehound plant, causing wilting of new shoots. They have five nymphal stages in their development. Although they usually attack horehound, they may also swarm on a variety of other trees and shrubs.

Control

Organic: Knock the swarm into soapy water or try spraying with pyrethrins. Chemical: Use demethoate or maldison to spray the swarm.

Reference

What Garden Pest or Disease Is That Judy McMaugh New Holland Publishers (Aust.) Pty Ltd.

Additional photos