Ask how often to feed and you will get a schedule. Schedules are convenient for keepers and irrelevant to spiders, which eat when they need to and stop for weeks when they do not.
Read the abdomen
The abdomen is the fuel gauge. A well-fed tarantula has an abdomen roughly the size of its carapace or a little larger. Noticeably smaller and it needs feeding. Much larger, tight and shiny, and it should be left alone: an over-fed spider with a distended abdomen is at real risk if it falls.
Practical portions
- Spiderlings: a prey item roughly the size of the spider's body, twice a week.
- Juveniles: one or two appropriately sized insects a week.
- Adults: two or three insects a month is plenty.
Appropriately sized means no longer than the spider's body. Larger prey is not dangerous to a healthy adult, but it is more likely to be refused and left to rot.
Refusals
An arboreal that ignores food for a month is usually in pre-moult. The signs: dull colour, a dark shiny patch on the abdomen, a sealed retreat, reduced movement. Remove live prey immediately, keep the water dish full and do not disturb the animal.
Other harmless reasons for refusals: a recent rehouse, a mature male on a wander, a cold spell in the room, or prey that is simply too big.
After a moult
Wait until the fangs have darkened before offering food, usually about a week for a juvenile and up to two for a large adult. Feeding too early risks damage to soft mouthparts.
Keeping the enclosure clean
Remove uneaten prey within 24 hours, and take out boluses when you can reach them. Feeder insects that survive in the enclosure will chew on a moulting spider, which is the one genuinely dangerous mistake in this article.