Sinobug

Hi Rob. Responding to your question on my blog.
My reference for Prionolomia gigas is Chinese and I believe is the original description of the species, so naturally it will list Yunnan, China as the origin. Chang Mai is a mere few hundred km away and it would be unlikely that a species range stops at a border. The species I see here in southern Yunnan are typically shared with Laos, Myanmar, Vietnam and northern Thailand and beyond. Similarly, I have photographed several insect species now officially recognized at the first records in China, yet when you look at the sightings maps, previous records all stop at the Chinese border. It is purely a question of who does the research or makes the spotting and where and whether information is pooled universally or restricted to probably language-based archives. I agree this looks like the Leaf-footed Bug, Prionolomia gigas (Coreidae), but at the very least it belongs to that genus.
John (SINOBUG)

Most definitely a Pseudophyllinae katydid nymph.
(The China link is mine. I was convinced it was a Phasmid to begin with as well. I have yet to encounter an adult but the chances of actually seeing it if it is right in front of you are pretty slim.)

@Jason Alexander
Like most Limacodids, they appear to be polyphagous. I believe this was on boxwood.

Tailed Yellow Owl (Neorina chrisna, Satyrinae, Nymphalidae)

@bayucca
Undeniable similarity to the linked Flickr images. All the indicators are that your Notodontidae 'hunch' are correct. At least my suggestion it was a Geometridae seem incorrect as it does in fact have 5 pairs of prolegs - the tails are one modified pair, it clearly has only two pairs of functional prolegs and there are two pairs of vestigial non-functional limbs there cranial to those. That alone would exclude the Geometridae as they have only one or two pair. That configuration is still very unusual even for the Notodontids and indeed with a brief browse through general images of Cerura caterpillars atypical of anything else I can see. But then, when is anything from Yunnan typical? Thanks for input and blazing a trail to follow....

Female Flower-tail or Cucumber Moth (Diaphania indica, Crambidae)

Stinging Nettle Slug Caterpillar (Cup Moth, Limacodidae)

Geometrid Moth, Fascellina sp., Ennominae, Geometridae

@Daniel Rowson
Body length was around 4cm....

Identified : Crambid Moth (Pagyda quinquelineata, Spilomelinae, Crambidae)