Dendrobium Beetle Stethopachys formosa The Destroyer!!!
As The Australian Orchid Nursery is located 75 kilometres south east of Melbourne we have no epiphytic orchids or ferns within 300 kilometres of us. As a result, there are no natural orchid pests such as Dendrobium beetles down here!
Our cold winters don't allow them to survive. It seems they start around Lakes Entrance in far east Victoria and then go all the way to Cape York in north Queensland. I have only seen them in the wild three times. Once at Merimbula on an isolated outcrop of Dendrobium speciosums, once at Brogo NSW, and finally on the Atherton Tableland munching on Dendrobium speciosum pedunculatums.
I would try Diazonon for an instant kill of the grubs, followed by Confidor pills to stop re-infection, then a Carbaryl spray over the leaves and blooms to take out the adults eating.
For those that like using the bigs guns for commercial control there is a PDF below on the subject. Its the online Wiley one.
If you have any tips for helping get rid of Dendrobium beetles, please comment below!
Over on our Facebook, Phil has one piece of advice that I'm sure has 100% effectiveness!
Here are some great links though to make you all experts.
Maybe condsider trying yellow or blue sticky traps next to plants.
Speciosum blooms are YELLOW!