>I don't know about DE for adult SHB. Those buggers are tough.
I have tossed out thousands of dead adult SHB when I change the DE in the SBB trays on my hives. I have watched them fly into it when I was putting the tray in and they are almost immediately disabled by its effects (they just lay there on their backs wiggling there feet). The havoc it causes to their respiratory system when they "breath it in" is far more detrimental to them than the "scrapes". I just make sure that it is deep enough (at least 1/4") so when they fall into it, they are instantly covered in it. It is a whole lot less mess and hassle than the oil.
>Also, the oil keeps anything from climbing out. DE won't, in and of itself, do this.
By my experience, what goes into the DE, never comes back out, even the larvae. They "tunnel" around in it for a short way but still succumb pretty quickly. The key is it must be "fluffy" and deep so that they are immediatly covered in it. Some insects that have longer legs and can just run through it will not suffer the respiratory effects, I have not observed this to be the case with SHB.
"The UNKNOWN, huh? That would be SNORBERT ZANGOX over in Waycross."