There are only a few poisonous spiders in Costa Rica, but within them the Banana Spider or Brazilian Wandering Spider which is sometimes considered the world’s most poisonous spider. A bite from this spider causes a loss of muscle control, and if untreated can eventually kill through paralysis and asphyxiation. The spiders are common in the jungles and banana plantations in Costa Rica, but most bites occur from spiders hiding in boots or socks.
Studies show that only 33% of the bites actually contain a significant amount of venom, but those that do contain it cause serious danger! It is also said that the bites of this spider are especially painful.
In case of a bite you should immediately seek emergency treatment!