Secure the room first
Close doors, block obvious gaps under doors and keep pets and other people out. Tell anyone in the house that a spider is loose so nobody vacuums, moves furniture or walks around barefoot without thinking.
Do not start by dragging every piece of furniture into the middle of the room. A startled tarantula can run from one hiding place into another while you are creating more disturbance.
Start close to the enclosure
Many escapees are found remarkably close to where they got out. Check behind and beneath the enclosure, shelving, nearby boxes, curtains and dark gaps. Use a torch from a low angle to catch reflections from legs or silk.
Look for routes rather than random locations. A terrestrial often heads for a dark ground-level gap. An arboreal may climb furniture, curtains or wall edges. A fossorial species may wedge itself underneath something that feels like a burrow roof.
Search methodically
Work around the room in zones and mark what has already been checked. Move one object at a time, inspect it, then put it somewhere that cannot immediately become a new hiding place.
Night-time searches can help because many tarantulas become more active when the room is quiet and darker. Keep the environment calm and check likely edges and shelters repeatedly rather than assuming one quick look was enough.
How to catch it safely
A clear catch cup and a piece of stiff card are usually the safest tools. Place the cup over or in front of the spider, encourage it inside without pinning a leg, then slide the card underneath and transfer it to a secure enclosure.
Do not grab a tarantula by hand or try to trap it with heavy objects. Fast Old World and arboreal species especially should be given a clear route into the cup rather than chased around the room.
If you cannot find it immediately
Leave safe water access in likely areas and reduce traffic through the room. Continue checking warm, dark, sheltered routes. Do not use glue traps, pesticides or other household pest-control products.
A missing tarantula can stay hidden for a long time, particularly if it found a secure crevice. Continue methodically rather than assuming it has left the property after a few hours.
Preventing the next escape
After recovery, identify the actual failure point. Common causes include unsecured lids, door gaps, ventilation holes that are too large for slings and opening an enclosure without a plan for a bolting spider.
Fix the enclosure before returning the spider. For rehousing or maintenance, clear the working area and have the catch cup ready before the lid opens. The best escape plan is the one that prevents a repeat.
Think like the species you keep
A useful search pattern starts with the spider's normal lifestyle. A terrestrial usually seeks low, dark shelter; a fossorial species may push beneath boxes, furniture or fabric; an arboreal may climb corners, curtains, shelving and textured walls. It is far more useful than searching every part of the room with equal effort.
Size matters too. A sling can enter gaps an adult could never use. Check cable holes, shelving joints, skirting gaps and the underside of furniture before assuming the spider travelled a long distance.
Use light and silence to your advantage
A darkened room and a torch used from floor level can reveal leg reflections, shadows or fresh silk that are hard to see under normal lighting. Keep the room quiet for a while before checking likely routes again; movement can resume once the disturbance has stopped.
Avoid leaving bright lights on all night. Make the room predictable and search it systematically.
After recovery, check hydration and condition
An escapee found after a long absence may be dehydrated or thinner than when it left. Return it to a secure enclosure with immediate access to clean water and allow it to settle. Do not respond by dropping in several feeders at once.
If the spider appears injured, cannot support itself or has an obviously damaged abdomen, treat that as a health issue rather than a normal post-escape settling period. A recovered spider that looks normal usually benefits most from water, security and quiet.
Common escape myths
Tarantulas do not usually roam the house with a destination in mind, and they are not hunting people or pets. Most are looking for somewhere dark, secure and structurally useful as a retreat.
An escape usually points to an exploitable lid, door or ventilation gap. Fix the mechanical cause and recheck every opening before returning the spider.
If the enclosure was left open
If you discover the door or lid open but do not know when the spider escaped, treat the room as the first search zone and do not assume it travelled immediately. Check the enclosure itself too; heavy webbers and fossorial species can be hidden in places that make an apparently empty enclosure look convincing.
Once you have searched the enclosure properly, close it so the spider cannot wander back in while you are moving objects around. Keep the search controlled and make a note of every place already checked.