Shield bugs grow up to 25mm long and are a serious pest of citrus trees. The young, flat nymphs are green when young, then orange before maturing to bronze or black adults.

The bugs suck sap and cause shoots to wilt and die and the flowers and fruit to fall.

Control:
Early in the morning, knock into a tin of water topped with kerosene. If there are too many for this, spray with a systemic chemical.

Apply in early spring while bugs are still juveniles. Check that the chemical is suitable for all citrus as kumquats, Seville oranges and Meyer lemons are sensitive.

Always wear goggles as these bugs can squirt a smelly, acidic liquid into your eyes.

Control them before they reach their adult, breeding stage, and then you may not see them again until the following spring.