buy a butterfly net and go through long grass for grass hoppers etc, under wood on ground for crickets etc
try mescalin salad, watties baby apples pureed,
others will have more info
buy locusts on trademe and get them shipped
good luck
scoria might also trap more detritus as well,
i use a grey and white coarse sand that the otnate blends into, it looked nice with plants but the silver dollars put paid to those.
another option is to just keep natives, there are a few different types and invertebrates as well, may need to keep the tank cooler in the summer months though
there are different types some harder
have kept blueys for a few years on both types no worries
get enough for 2 pieces 1 in tank while you wash the other
can either get edges done by rug binding or melt with a lighter to get rid of frayed bits