Scale insects

Researcher Rosa Henderson from Landcare Research NZ Ltd introduces the tiny scale insects and talks about their role in the ecosystem.

Transcript

ROSA HENDERSON The scale insect is part of the large order called Hemiptera, which are all sucking bugs. The scale insects have evolved into rather specialised and reduced morphology, so they tend to be little soft-bodied animals that don't grow up, if you like, to an adult thing like a beetle or a fly and fly around. They sit attached to a plant and they suck the sap from the plant. They have specialised mouth parts, which are called stylets, and they insert these into the plant and either suck up from the phloem or from within the plant cells. Honeydew is a resource that is produced by the scale insects they are feeding on the phloem of a plant. They have to process a lot of it to get what they want. There is a lot of sugar, which they don't too much of. There is not much nitrogen, which they do need a lot of. So they really just process it through their body and out the other end. They have to be very careful not to get themselves covered in it or they get moulds and fungi growing on that sugary substance that can then suffocate them and kill them, so they have various means of getting rid of this sugary substance. The sooty beech scales in the beech forests of the South Island, in particular, have a long anal tube, and the honeydew is dropped off the end of that, so it’s ideal for other animals to come along and sip on that little drop as it forms.

Acknowledgements: Landcare Research New Zealand Limited Maree Reveley Jon Sullivan Matt Walters, University of Canterbury