Katydid
Date: 14 Aug 2002 Author: Jianhua Mo
Three species of katydids are found in the Riverina area, causing minor to occasionally important problems for citrus growers.
Description
- Grasshopper-like insects with thin, long antennae (usually longer than body).
- There are three species of katydid in Australia:
- citrus katydid
- inland katydid
- spotted katydid.
- Adults are green to brown, and 40–50 mm long.
- There is one generation per year.
- Eggs are laid from January to April.
- Nymphs hatch in early spring and develop through five stages.
- Adult stage is reached during December–January.
Damage
Deep chalk-like scars on the fruit surface
- Nymphs and adults feed on citrus flowers, fruits and leaves.
- Feeding on fruits results in fruit drop or deep chalk-like scars on the fruit surface (see image).
- Damage is more common in oranges than in lemons, grapefruit or mandarins.
Natural enemies
- Parasites: an unidentified tachinid fly species, and an unidentified wasp species.
- Predators: assassin bug, praying mantises, sphecid wasps, and birds.
Monitoring
- Monitor every 2 weeks from mid-September to late November.
- On each occasion, check five randomly selected fruits from each of five randomly selected trees.
- Use sticky trunk bands to monitor the numbers of emerging nymphs.
Control measures
- Action should be taken when 5% or more fruits are showing fresh injury, or when sticky bands have more than two emerging nymphs per tree.
- Use a selective insecticide in areas of the orchard where the action threshold is exceeded.