are these eggs and insects on the undersides of my canna leaf? I've
also seen them on grapes. Are they green beetles?
look like the eggs and young (nymphs) of the green vegetable bug
which some gardeners call shield beetles or shield bugs.
The nymphs change colour
as they develop from orange to shiny black and eventually to the
green of the mature adult, though there is a relatively rare variety
which is orange at maturity. They feed by stabbing their sharp hypodermic-like
mouthparts into soft plant tissue and suck the sap.
You generally find them
in warm sunny spots in the garden. They'll drop to the ground or
fly away if disturbed. It's not uncommon in a late summer evening
for them to be attracted to bright lights and come indoors where
they can blindly fly around. They exude a foul-smelling liquid if
provoked, hence their other common name of "stink bugs".
They can be a major pest
of susceptible plants like tomatoes, beans and passionfruit, causing
deformed growth, lack of vigour and poor fruiting, but are seldom
a problem among ornamentals. Most common broad spectrum insecticides
can be used to control them if necessary.
Gardener, Issue 180, 2005, Page 32
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.