The largest spider in Thailand is the Huntsman spider. It can have a leg span up to 12 inches (30 centimeters). The largest version is called the Giant Huntsman, and its said to have been first discovered in 2001 in Laos. However, the mushroom hunters and forest monks of Sakon Nakhon will tell you that they have long known of giant Huntsman spiders. They view them simply as large, ordinary Huntsman spiders — the Thai name being Maengmum Panayjon (แมงมุมพเนจร), which translates to the wandering spider.
While we personally have yet to see a Huntsman spider with a 12 inch leg span, we have certainly seen ones with around an 8 inch span in our farmhouse, which exceeds the span of the large Thai Zebra Tarantula. When it comes to seeing Huntsman spiders indoors in Northeast Thailand, that would usually be in an older wooden house, or a rustic Sakon Nakhon hotel or guesthouse, during the cool season (November – February). Huntsman spiders do not spin webs and are very fast, because they need to move fast to catch their prey. Being the largest spider in Thailand, it is not surprising that their prey can include small lizards and frogs, as well as insects.
Now, to answer the question you are probably thinking to yourself, “Is the biggest spider in Thailand dangerous?” You’ll be happy to hear that it is not. Although it is possible to get bitten by a Huntsman spider, you would have to be really antagonizing it. Even if bitten, the venom is mild. So, it is not dangerous to people. They are generally quite scared of humans. So if you see one, it is best to just ignore it or take a broom and shoo it away.
However, note that when trying to shoo a Huntsman spider away, it might suddenly come running toward you! Don’t worry. It is not trying to attack you. It is just confused, and actually trying to run away from danger of your broom attack. But sometimes (in their confusion) they will flee toward you instead of away.
Now, if you try to actually swat the Huntsman spider in an attempt to kill it (which we do not recommend because they are harmless), note that they often will scrunch themselves up in a manner which makes them look dead. This gives you an opportunity not to finish them off, but rather sweep them outside, so that they can go on their merry way and live to see another day.