Subject: Guava (?) caterpillar
Geographic location of the bug: North Queensland, Australia
Time: 08:27 PM EDT
Your letter to the bugman: We found this large, colourful caterpillar on a guava tree today (Autumn). It is about the size and thickness of my thumb. What is it? What will it become? Is it harmful?
How you want your letter signed: Connie
This is a Giant Silkmoth Caterpillar in the family Saturniidae, and we believe we have correctly identified it as the Emperor Gum Moth Caterpillar, Opodiphthera eucalypti, which is pictured on Butterfly House. According to Butterfly House: “Cherry Guava ( Psidium cattleyanum )” is listed as a food plant. The Emperor Gum Moth Caterpillar is also pictured on Jungle Dragon and on the Woodlands Historic Park site. Another possibility is that this might be Syntherata leonae, a species with no common name whose caterpillars are described on Butterfly House as: “Later the caterpillars become olive green with a yellow line along each side, and have pink-tipped tubercles each of which has a cluster of short stiff hairs.” The latter species is also pictured on Aus-Lep. Neither is considered harmful. Perhaps someone with more expertise in Australian Saturniids will be able to provide more clarification.
Update: Thanks to a comment from Matthew Connors, we are concluding that this is Syntherata escarlata.