With the limited number of desert blocks you can mine around the island with the desert pylon (hardened sand, sandstone), I don't manage to get desert mobs to spawn.

I first made a huge horizontal line made of the two desert blocks: the spawns from outer screen weren't desert mobs.

I converted a few of them into background walls, laid them above the desert blocks, placed myself at spawn distance... it still weren't desert mobs that spawned.

Only exception is the larvae, sometimes, some of them do spawn, but they're not useful for anything alas. I need antlions.

I'm lost.

I have no way of expanding my desert biome and generating sand, thus, no?

Thanks a lot if someone can help, really, I'll be most grateful!