Our first cicada for months – perhaps since January – flew in through an open window last night. They seem to start appearing around the end of October each year, nymphs digging their way up out of the ground to climb up any convenient plant stem or trunk and split open to emerge as winged adults like this one. Here is the adult of another species from last year.
They look like they ought to be classified with grasshoppers and katydids, in Orthoptera, but in fact they are grouped with shield bugs and the like in Hemiptera. Why? Because they suck sap rather than chewing leaves. Wikipedia has a good general article about them if you want to know more.
Update, 21 November: I found the cast-off shell (exuvia) of a cicada nymph hanging beneath a pentas leaf. It is probably not the shell of the cicada above and may not even be the same species, but it must be similar and you can see it here on Flickr. Note the split down the middle of the back which the adult insect emerged from.