Bugs grow big in Thailand; besides their frightening size, most of them can pack a painful bite or sting, and some are even deadly. Read this before you start messing with Thailand’s most dangerous insects and bugs.
The “rule of bugs” in Thailand: Treat them all as potentially harmful, leave them well alone, and seek medical advice if you are bitten or stung.
Mosquitoes
You’ll find mosquitoes in Pattaya, Bangkok, Chiang Mai, and just about anywhere you go in Thailand. They may not look fearsome or have a painful bite, but they can transmit potentially life-threatening diseases such as dengue fever and malaria, perhaps putting them right at the top of the list of dangerous things in Thailand.
Fortunately, you can easily buy mosquito repellents in Thailand, typically containing around 15 percent DEET.
Sand Flies
Sand flies are worth mentioning here, as their bites are easily mistaken for mosquito bites. Their bites can be extremely irritating, leading to scratching and the risk of secondary infection. They are common on many beaches and in mangrove forests, such as the Prasae Mangrove Forest in Rayong.
The Giant Centipede
This monster centipede (see photo above) is commonly known as the Vietnamese Centipede or Asian Forest Centipede. The giant centipede can grow up to 15 inches long in Thailand. It is a fearsome predator and will bite if provoked.
The giant centipede has a venomous bite that’s said to be excruciatingly painful and might cause infection or other complications. I rate the giant centipede as the scariest bug in Thailand.
Hornets and Wasps
You might encounter the Asian Giant Hornet in some parts of Thailand, but more commonly you’ll see the greater banded hornet (Vespa tropica) and the lesser banded hornet (Vespa affinis). They’re not as large as the Asian Giant Hornet, but large enough to be easily mistaken for one.
Hornets are renowned for their aggression when provoked or encroached upon. They grow to huge proportions in Thailand, making them bugs you don’t want to mess with.
It’s common to have a hornet circling around you, seemingly checking you out. Most people’s first reaction is to run like hell. Having a garden and living in a relatively green area of Pattaya, I often get visited while sitting outside, and I can assure you, if you stay still, they will soon go away.
By all accounts, hornet stings can be extremely painful. I have heard the pain described as searingly hot and comparable to an electric shock. If you search around, you’ll find instances where stings have resulted in heavy swelling and even severe reactions.
Paper Wasps: At first glance, you might mistake them for a hornet, but paper wasps bear more resemblance to a large flying ant. The Paper Wasp has an elongated body, often marked with black and yellow bands, though colors vary by species. They often appear to be bumbling around like they are lost. They are quite docile, but they can give a mildly painful sting.
Bees
Thailand is home to several honeybee species, including the Asian honeybee (Apis cerana). They’re generally docile and vital pollinators, but like hornets and wasps, they can deliver a painful sting if disturbed.
You’ll sometimes see honeybees gathering around stalls selling sweet food and drinks, like the ones I photographed at a cart near Tukcom in Pattaya (photo above). The lady selling drinks here carried on as if the bees weren’t there.
Spiders
There is no shortage of big, hairy, scary spiders in Thailand, including tarantulas, black widows, giant orb weavers, and huntsmen. And some potentially dangerous ones, such as the Black Widow, Brown Widow, and Mediterranean Recluse, although reports of lethal or serious bites are extremely rare.
Scorpions
Scorpions are found mainly in forests and rural areas of Thailand, but can also be encountered in cities, especially near scrubland or parkland
There is many a traveler’s tale on the Internet describing encounters with scorpions in Thailand. The encounters usually result in someone getting stung by a scorpion when putting on their shoes or getting dressed.
The pain from scorpion stings in Thailand can range from that of a bee sting to much more intense, with smaller species often considered more venomous and painful.
Like most insect bites and stings, there is a risk of allergic reaction, which can be serious, so medical attention is advised if symptoms are severe.
Caterpillars
Although they are often very beautiful and colorful, there are some species of caterpillar in Thailand that are considered dangerous, one such example being the Stinging Nettle Caterpillar. The spines of the caterpillar are similar to strands of fiberglass; they stick to the skin and are extremely irritating. The real danger is if they get in your eyes, in which case you should seek medical help.
More Nasty Bugs in Thailand
Some ant species found in Thailand, especially fire ants on the ground and red weaver ants in trees, can give you a nasty nip. Be especially wary of fire ants if you’re a golfer; if you happen to tread on a nest, they’ll be biting their way up your leg within seconds.
Ticks are mainly a problem for dog owners in Thailand, but you might come into contact with them if you spend time hiking or in rural areas. Their bites cause irritation and swelling, and reportedly a small risk of tick‑borne diseases.
Leeches are common in Thailand’s forests, wetlands, and freshwater streams and ponds, especially during the rainy season. Although leech bites are not usually considered dangerous, as with other bites and stings, there is a risk of secondary infection.
A Fearsome But Not Dangerous Bug in Thailand
At some point during your stay in Thailand, you have a Praying Mantis inadvertently land on you. Don’t be alarmed, they are quite harmless, you may be able to coax it onto its back legs and box your finger, it might bite you if it becomes annoyed, but it only delivers a slightly painful nip.