A couple of weeks ago I made a terrarium/vivarium for my tree frogs -- one for 2 green tree frogs, the other for 2 young white's tree frogs. Both have leaf litter and sheet moss as the final layer. Both have one width of tree fern panels on each side and a background on the back.

The problem is I find crickets hiding behind the tree fern panels (which have a little gap -- tried to get them flush with the side but there's still a little gap), under some of the sheet moss, and around the leaves. I see 4 or 5 crickets hiding in the White's enclosure mainly behind the tree fern panels -- haven't seen any in the green tree frog's enclosure but have seen crickets go under the sheet moss.

What can I do to close the gap with the tree fern panels -- maybe put some coconut fiber back there? I can try to rearrange the moss so that the crickets have less of an opportunity to get under it -- should I take out the leaves? There is coconut fiber beneath the leaf litter layer.

Any advice on this would be appreciated. I'm worried about my White's -- they seem to be getting a little thinner.