It is probably in the same genus as the twice-stabbed lady beetle (Chilocorus), but probably a different species.

There is, if memory serves, a Chrysomelid 'mimic' of the twice-stabbed ladybug. I'll do some digging. I guess memory is the first thing that goes, or maybe not, can't remember.

I, too, thought it was a tortoise beetle, but given the heads-up from you I looked into the Twice Stabbed lady beetle. I'm convinced that you are correct.

I don't remember seeing a tortoise beetle that resembles the twice-stabbed lady beetle. Although, you son is correct the tortiose beetles have a translucent shell. See twice stabbed here. See Tortoise Beetles here.

The puzzling feature of this insect is that it does appear to have a translucent elytra, although its pattern suggests it is related to the Twice Stabbed Lady Beetle, which also appears to have translucent elytra. I'm scratching my head, and am going to tell my son that it's probably not a tortoise beetle, it could be a Twice Stabbed Lady Beetle, but no one is sure what it is at this point.