Most escapes are not dramatic. A door left a few millimetres open, a lid that did not seat, a ventilation hole drilled a size too big. The spider does the rest at three in the morning.
The rule
A tarantula can pass through any opening large enough for its carapace, and spiderlings can pass through openings that look impossibly small. In practice, keeping every opening at or below 3 mm is the line that holds for spiderlings of the species most people keep, which is why every hole in a T-LOVER enclosure is a 3 mm hole and nothing larger exists anywhere in the build.
The checklist for any enclosure
- Door and lid seams: run a fingernail along all four edges. If it catches in a gap, so can a leg.
- Ventilation holes: measure a few. Drilled holes are often larger than the drill bit suggests, and burrs make them larger still.
- Corners: where two panels meet is where badly built enclosures leave a triangular gap.
- Cable and feeding ports: a port with a rubber grommet that has hardened is a hole.
- The lid, when full: put substrate and cork in, close it, and check it still seats flush.
Locks that survive a distracted evening
Clips get lost. Tape peels. Magnets that pull the door closed with an audible click are the only mechanism that also works when you are tired, and recessed magnets sit flush so the mating faces stay clean. On the Arboreal Paradise Adult the door slides to the left and locks to the right on three of them.
Burrs matter more than people think
A sharp burr on the inside of a ventilation hole will catch a tarsal claw and can tear it off. Every drilled hole should be deburred. Run a cotton bud around the inside of a few holes in any enclosure you are considering: if it snags, so will a foot.
If a spider does get out
Close the room and turn off any fans. Look high first: door frames, curtain rails, the tops of picture frames. Use a large clear container and a stiff card, work slowly, and remember that a spider that has been out for hours is usually sitting still somewhere dark and elevated, not running.