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Dangerous animals, plants & fungi in Chiang Mai region
Go to: Mosquitoes (itching, allergies, disease vector)
Dogs (bite, infection, rabies)
Cats (bite, infection)
Snakes (bite, envenomation)
Centipedes (bite, infection, pain)
Scorpions (sting, mild pain)
Spiders (bite, various reactions, pain)
Ants (bite, sting, mild to strong pain)
Flies (itching, allergies, disease vector)
Wasps & Hornets (sting, various reactions, pain)
Ticks (disease vector)
Other insects (bite, sting, various reactions)
Other mammals (bite, infection, disease vectors)
Mushrooms (poisoning)
Plants (poisoning, various reactions)
A few harmful animals & others live in Chiang Mai area. Although, ultimately, the most dangerous (when actual risk is taken into account) are the one most people would know about (such as dog bites, bee stings and mosquito-borne diseases), it is always good to know other problematic species around Chiang Mai.
With the exception of some parasites and blood-sucking animals, most animals will only bite or sting when directly threatened, so when unnecessary or when you are not sure, just don’t bother animals and they are likely not to cause you harm.
The list below does not go into details of parasites and infectious agents carried by some of these species as this topic is covered here. Keep in mind that these are standard reactions to bites/stings/contacts but allergies, anaphylactic shocks and various infections can make things worse.
MOSQUITOES
Itch, Infection, various diseases
By far the most problematic animal in Thailand. It is a common pest in all humid areas and they become particularly abundant when the raining starts in May-June to the end of the wet season in November.
The mosquito bite itself is often just a nuisance that cause mild irritation. There are some exception of strong allergic reaction (i.e. Skeeter syndrome) which can require some medical treatment.
Beside the itching issue, the main reason to avoid mosquito bites is that mosquitoes are vectors to several diseases that cannot be ignored when traveling or living in Thailand. These diseases include the most common Dengue & Zika fevers, Japanese Encephalitis, Malaria, Chikungunya and Elephantiasis.
The following species are of particular concern in Thailand:
Yellow Fever Mosquito (Aedes aegypti): Dengue Fever, Zika Fever, Chikunguya, Yellow Fever (rare), Elephantiasis (rare)
Asian Tiger Mosquito (Aedes albopictus): Chikungunya, Dengue Fever, Zika Fever, Elephantiasis (rare)
Culex gelidus: Japanese Encephalitis, Elephantiasis (rare)
Culex tritaeniorhynchus: Japanese Encephalitis, Elephantiasis (rare)
Anopheles dirus: Malaria (rare), Elephantiasis (rare)
Anopheles minimus: Malaria (rare), Elephantiasis (rare)
Mansonia sp.: Elephantiasis
Prevention: Avoiding mosquito infected areas and/or use preventive measures such as mosquito nets, repellents and insecticides.
Treatment: Anti-itching creams, hydrocortisone. In case of more severe reactions and infections, consult a doctor.
Common Thai mosquitoes: a. Aedes aegypti, c. Culex tritaeniorhynchus, e. Anopheles dirus
b. Aedes albopictus d. Culex gelidus, f. Anopheles minimus
Source: wikimedia, Walter Reed Biosystematics Unit, Hong Kong Centre for Health Protection, CDC/wikimedia, iNaturalistNZ
DOGS
Bites, Infection, Rabies and other diseases
A common encounter in Thailand in urban and rural areas and arguably the most common 'wildlife' threat that affect the human population. A large number of dogs in Thailand are strays and a lot of them have mistrust in humans enough to be aggressive and promptly biting in some situation. In addition, most dogs (stray or not) are unlikely to be vaccinated and can be the carrier of diseases such as rabies and a large number of viruses, bacteria and other parasites.
Prevention: Avoid touching or approaching unknown dogs; take appropriate actions if chased by dogs. Rabies vaccination is strongly recommended for long term residents in contact with stray dogs.
Treatment: Clean the wound with water, soap and iodine-based disinfectant for 15 minutes. If bitten, consult a doctor immediately so that the best approach can be taken. Untreated rabies has ~100% mortality rate so it is essential to seek professional advice after such incident.
CATS
Bites, Infections, some diseases
Cats are less likely to carry disease that are critically problematic to humans. However, scratches and bites can lead to an infection and should be cleaned properly.
Prevention: Avoid touching stray cats.
Treatment: Clean the wound with water, soap and iodine-based disinfectant for 15 minutes. Rabies and severe infections remains possibilities (although less likely than dog bites) so keep an eye on the wound healing progress and other symptoms and consult a doctor if needed.
Typical asian village dog & cats in Thailand
Source: Warren Photographics
SNAKES
Vipers, Cobras, Kraits & Co : Deadly bites
As a general advice, keep your distance with snakes, particularly if you are not absolutely certain of your species identification skills.
Non-venomous snakes: A bite is always possible and these can become infected. Most tree-snakes, rat-snakes, cat-snakes, whip-snakes, keelbacks, pythons fall in this category.
Keep in mind that large pythons are a threat to children, small individuals and pets.
Venomous snakes: There are a number of snakes in Chiang Mai that requires some urgent medical attention when bitten.
PIT VIPERS (Calloselasma rhodostoma; Trimeresurus albolabris; Trimeresurus macrops): Necrotoxic venom with high toxicity - potentially deadly - seek medical attention to a hospital where an anti-venom is likely available.
Do not wrap a tight bandage around the bite as it is best for this venom to be diluted by blood flow.
COBRAS
- Monocled Cobra (Naja kaouthia): Neurotoxic & Cytotoxic venom with very high toxicity - deadly - seek medical attention urgently to the nearest hospital even for small bites from small individuals (Faiz et al., 2017).
- King Cobra (Ophiophagus hannah): Neurotoxic & Cytotoxic venom with high toxicity - deadly; seek medical attention urgently to the nearest hospital (Ganthavorn et al., 1971).
- Spitting Cobra (Naja siamensis): Neurotoxic & Cytotoxic venom with high toxicity - deadly; can also cause damage to eyes; seek medical attention urgently to the nearest hospital (CTR, 2018).
Pit Vipers (from left to right): Malayan Pit Viper (Calloselasma rhodostoma) - White-Lipped Pit Viper (Trimeresurus albolabris) - Large-eyed Pit Viper (Trimeresurus macrops)
Source: Thai National Parks
Cobras (from left to right): King Cobra (Ophiophagus hannah) - Monocled Cobra (Naja kaouthia) - Spitting cobra (Naja siamensis)
Source: Arief et al., 2021, Thai National Parks, Nakhon Ratchasima Zoo
RED-NECKED KEELBACK (Rhabdophis subminiatus): Very high toxicity - potentially deadly - this snake requires a long bite to inject its venom. If bitten, remove it as quickly as possible and seek medical attention. There is no antivenom available in Thailand (Ferlan et al., 1983).
BANDED KRAIT (Bungarus fasciatus): Neurotoxin with very high toxicity but rarely injects large quantities - deadly - seek medical atention urgently to the nearest hospital even for small bites from small individuals (Tongpoo et al., 2018).
The information above is a list applicable to Chiang Mai (and Northern Thailand) only. Other parts of Thailand have other species of venomous snake you have to be aware of.
Prevention: Avoid approaching snakes
Treatment: it will vary on the type of snake. As a general advice, follow this link from Bumrungrad Hospital.
Left: Red-necked keelback (Rhabdophis subminiatus) - Right: Banded krait (Bungarus fasciatus)
CENTIPEDES
Bite, Pain, Infection, mildly dangerous
Not to be confused with millipedes (many many legs), centipedes are carnivorous arthropods with large mandibles capable of causing very painful bites (Yang et al., 2015).
Red-headed Chinese Centipede (Scolopendra subspinipes): Neurotoxin of mild toxicity - the bite is extremely painful, causing a burning sensation for several days and a possible infection. Medical attention is advisable in case of severe bites.
Prevention: Most bites are accidental as the Red-headed chinese centipede is very aggressive.
Treatment: Clean the wound with water, soap and iodine-based disinfectant and observe for worsening symptoms or signs of infection.
Chinese red-headed centipede (Scolopendra subspinipes)
Source: Mans, 2017
SCORPIONS
Sting, Pain, mildly dangerous
Thai scorpions can be quite large but none of them are very dangerous. Their sting are similar to bee/wasp stings. As a general rule, the larger the pedipalps (=pincers) the less likely a scorpion will sting and/or has a powerful venom. Reaction to the sting site can however become unbearable and might require medical attention.
Giant blue scorpions (Heterometrus spinifer & laoticus): very large, black-bluish. They have crab-size pincers but relatively unwilling to sting. The venom has a mild toxicity (van der Meijden et al., 2017; Nirthanan et al., 2002; Uawonggul et al., 2007).
Chinese swimming scorpion (Lychas mucronatus), Bark scorpion (Lychas scutilus) & Lychas krali are common medium size beige-brown scorpions. Venom has a mild toxicity but they commonly sting. (CTR 2018).
Isometrus (maculatus & vittatus): medium size stripy brown scorpion. The venom can cause swelling and nausea (Yates, 1993).
Dwarf wood scorpions (Liocheles (australasiae & nigripes): medium size reddish to yellowish brown scorpions with short tails. Venom toxicity is relatively high but not much information on symptoms (Habermehl, 1981).
Other scorpions species are found in Thailand (Thaicharmus mahunkai; Scorpiops farkaci; Euscorpiops binghamii; Scorpiops longimanus,...) but little information on their dangerosity is available.
Prevention: Stings are hardly preventable but avoiding nesting places is recommended.
Treatment: Clean the sting site with water, soap and iodine-based disinfectant and observe for worsening symptoms or signs of infection.
Common Thai scorpions: a. Giant blue scorpion (Heterometrus sp.) b. Chinese swimming scorpion (Lychas mucronatus)
c. Bark scoprion (Isometrus sp.) d. Dwarf wood scorpion (Liocheles sp.)
Source: own material, wikimedia, Evenhuis et al., 2010
SPIDERS
Bites, envenomation, mildly dangerous
Most spiders are harmless or cause very mild bites with no problematic venom. However a few have to be kept in mind for Chiang Mai area:
Redback spiders (Latrodectus sp.): Black-widow type of spider, causing painful bites and injection of a neurotoxin that often requires medical attention. Very rarely deadly but concerning enough to avoid close encounter (Offerman et al., 2011).
Huntsman (Heteropoda sp.): Large and quick spiders frequently wandering in houses. Their bites are not intrinsically dangerous, but some bite (H. venatoria) can be painful) but local necrosis is always possible and could require medical attention. Only mentioned in this list because of their size.
Yellow sac spider (Cheiracanthium punctorium): Small spider living in a silk tube under leaves, wood pile and house corners. Sharp fangs can produce a neurotoxic bite which can be serious (Varl et al., 2017).
Tarantula spiders (Cyripagopus sp.): There are three tarantula species in Chiang Mai, the cobalt blue T., the zebra T. and the Thai black T.; All are big, aggressive and have a strong venom causing cramps and inflammation. The cobalt blue lives in the rainforest, the zebra is more common in farmland and the black is rarer and mostly in humid forests (Takaoka et al., 2001).
Wolf spiders are medium size arachnids, generally not aggressive but will bite if continuously annoyed. The bite is generally not problematic but if symptoms persists, consult a doctor.
Giant golden orb-weaver spider (Nephiila pilipes): These are long-legged medium-size spiders living in the middle of (sometimes gigantic) spiderwebs. Scary but the bite seems rare. However, it is possible that the bite causes acute muscular symptoms.
Jumping spiders: unlikely to bite, but some have venom that can cause a local reaction and in some rare cases, more general symptoms (diarrhea, headache, nausea).
Prevention: Bites are often accidental and hardly preventable but avoiding nesting places is recommended.
Treatment: Clean the bite site with water, soap and iodine-based disinfectant and observe for worsening symptoms or signs of infection.
From left to right: Black widow (Latrodectus elegans) - Huntsman (Heteropoda venatoria) - Yellow-sac spider (Cheiracanthium punctorium)
Source: Wikimedia, Thailand Nature Project, Paolino et al., 2021
From left to right: Cobalt blue tarantula (Cyriapagopus lividus) - Thai Zebra leg tarantula (Cyriapagopus albostriatus) - Thai Black tarantula (Cyriapagopus minax)
Source: Birdspiders.com ; own material
From left to right: Wolf spider (Pardosa pseudoannulata) - Jumping spider (Plexippus paykulli) - Giant golden orb-weaver (Nephiila pilipes)
Source: iNaturalist UK, Edwards, 2011, Thailand Nature Project
ANTS
Itch, Pain, rarely dangerous
Most ants can bite but are relatively harmless. Some allergic reactions have to be kept in mind.
Sugar ants (tiny black ants getting into everything) are very aggresive and bite readily but are so tiny that it is more a nuisance than pain.
Fire ants (red ants) have a sting producing a sharp pain followed by a skin reaction a few hours later. Treatment includes antihistamine and corticosteroid for severe cases but a doctor should be consulted in case of infection or allergic reaction.
Red weaver ants are aggresive and produce a mild bite accentuated by the number of bite that often occur when a nest is disturbed. Commonly used by rural Thais to protect fruit trees and for collecting eggs for food.
Some less common species of ants have a very strong bite that feel like a wasp sting but the pain often goes away relatively quickly (in a matter of minutes)
Prevention: Bites & stings are accidental and hardly preventable but avoiding nesting places is recommended.
Treatment: Clean the bite site with water, soap and iodine-based disinfectant and observe for worsening symptoms or signs of infection.
FLIES (all types)
Itch, Pain, Diseases, rarely dangerous
Thailand is no different than other places in the world, some flies are blood-sucking and can cause itchiness and irritation. These flies include sand flies, black flies, horse flies, highland midges, etc. Some flies, such as the house fly, are vector to bacteria infection of Salmonella or E.coli while sandflies can be carrier for Leishmaniasis.
BEES, WASPS, HORNETS
Sting, Pain, Infection, rarely dangerous
A considerably number of bee species exist in Thailand, from the stingless bees or very tame dwarf honey bees) to more aggressive type such as carpenter bees. Sting varies from species to species. Some wasps and hornets can be aggresive and stings will cause intense pain and necrosis at the sting site. Cases of allergies, infection and prolonged reaction should be observed by a doctor.
TICKS
Infection, rarely dangerous
Common blood-sucking parasites in grassy areas, ticks can cause irritation and infection at the biting site. The number of tick species in Thailand is very high and some can be carrier of diseases, others not. However, overall, the risk of catching a tick-borne disease in Thailand is lower than in temperate country. Possible diseases from ticks include typhus, Q-fever, Babesiosis, Erlichiosis, etc. Borrelia, the bacteria causing Lyme disease, is almost absent in Thailand and is a very low risk in South-East Asia.
MONKEYS
Bites & scraches, infection, tetanus, rabies, Herpes B, etc., midly dangerous
Macaques can be aggresive in touristic areas and lead to scratches and bites. In additiion to the possibility of infection with tetanus and rabies, be aware that macaques can be carrier of the potentially deadly Herpes B virus. It is very unlikely you would get monkeypox from a monkey.
Prevention: Avoid touching monkeys or being touched by monkeys.
Treatment: Clean wound with water, soap and iodine-based disinfectant for 15 minutes
If bittent, consult a doctor immediately so that the best approach can be taken without delay.
BIG CATS
Bites, theoretically deadly
Indochinese tiger is the only species of tiger hypothetically living in the North, in the Western Forest Complex. The chance to see one by accident (or for that matter on purpose) in the wild are very slim
Indochinese leopard (also including black panther) is almost as rare as the indochinese tiger and is occasionally recorded on wildlife camera in the Western Forest Complex. The chance to see one in the wild are slim and there is no concern to have.
Wild cats (Jungle cat, Fishing cat, Asian golden cat, marbled cat, leopard cat) are small feline species living in Northern Thai forests. They are very shy and the risk to have a problematic encounter is very slim.
ELEPHANTS
Trampling, charge, deadly
Keep your distances with wild elephants and possibly take preventive action to make sure you keep your distances. Thailand has a record of tens of deadly encounter every year
As a matter of precaution, do not approach a domesticated elephant without supervision
Other insects
Giant water bugs are a group of insects able to inject a venom through stinging mouthparts. The bite can be extremely painful although generally not dangerous.. These are called toe-biters in other part of world for a reason and it's best to avoid them
Prevention: Avoid going in standing water without appropriate footwear.
Some rove beetles (Paederus fuscipes & Philonthis paederoides) can cause dermatities (reddish rash, blisters, crusting and scaling) when crushed against the skin or in contact with the infected skin (Sirikajongjaru, 1994).
Prevention: Hand and skin washing with soap is recommended if a contact with a rove beetle occured.
From left to right, top to bottom: Crab-eating macaque (Macaca fascicularis) - Indochinese Tiger (Panthera tigris) - Indochinese leopard (Panthera pardus) - Asian elephant (Elephas maximus)
Source: Wikimedia, WildlifeThailand, Pratya Chutipaskul
Left: Giant water bug (Lethocerus indicus) with front legs and biting mouthparts visible - Right: Rove beetle (Paederus littoralis)
Source: own material, wikimedia
MUSHROOMS
Thailand is not different from any other country. Refrain from picking and/or eating mushrooms if you are unable to identify them. Some amanita are deadly, many other will make you sick. As a reference, Parnmen et al., 2016 might be useful.
Prevention: Avoid picking unknown mushroom and/or wash your hands after touching them.
PLANTS
A large number of plant are unsuitable for human consumption, irritant, itchy, spiky, etc. and cannot be all mentioned here. Below are some common encounters.
Velvet beans (Mucuna pruriens) is a plant that produces beans causing extreme itchiness on contact (the original itching powderand is quite common in rural areas.
There are no efficient medical treatment. Physical removal (energetic shower) from the skin of tiny hairs covering beans pods is necessary to remove the itchiness quickly
Physic nut (Jatropha curcas) is a plant that cause more than 50% of plant poisoning in Thailand (Sriapha et al., 2015).
Cassava (manioc, yuca) (Manihot esculenta) is the highest cause of plant-ingestion mortality in Thailand as cassava is considerably toxic when raw (Sriapha et al., 2015).
Dumb cane (Dieffenbacchia maculata) is a common ornamental plant that cause severe irritation and is particularly problematic for young children.
Pong pong tree (Cerbera odollam) is a common ornamental tree. The fruits contain cerbering, a chemical causing cardiac arrest and ingestion is often deadly.
Fish poison tree (Barringtonia asiatica) is a toxic tree sometimes found in urban environments.
A large number of tropical fruit trees have sap that are extremely sticky and/or irritant. Contact with sap from these trees, freshly cut fruits, etc. should be avoided.
Keep in mind that some trees (coconut, jackfruit, durian) have particularly large heavy fruits that can drop unexpectedly and cause serious injuries.
References
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Clinical Toxinology Resources. (2018). Naja siamensis. University of Adelaide, http://www.toxinology.com, Item SN0045
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