I have used various versions of amorphous silica as an insecticide.  There are s
everal drawbacks to its use.  1.  The dust is irritating (not toxic) to people,
particularly to anyone who has respiratory allergies.  It is, indeed, what
 the
safety people here call a "nuisance dust".  2.  The insects have to track throug
h the dust for it to be effective.  Dermestids don't tend to walk around much ge
tting to their food.  The adults fly in and don't hit the powder before they
 lay
 eggs.  3.  The dusts are abrasive and could create problems in mechanical syste
ms.  They are also theoretically damaging to artifacts, particularly fibrous one
s such as textiles.  4.  It is impossible to keep the dust totally restrained
and it will eventually contaminate everything in the area.  However, if the inse
cts do track through it, the dust probably works.  It is most usually intended t
o control cockroaches, which it may do fairly well as they do scurry around
under things.  Good Luck
 
Geoffrey Brown
Kelsey Museum, University of Michigan