Top 10 Most Dangerous Insects in Vietnam You Should Know

Stinging Ants, scientifically known as Paederus fuscipes, belong to the Staphylinidae family and the Coleoptera order. These insects have slender, rice-sized bodies measuring 1-1.2 cm in length and 2-3 mm in width, with red and black coloring. Despite not actually being ants, they are often referred to by various names like wandering ants, shiny ants, rice ants, and others due to their appearance.

Stinging ants are commonly found in both urban and rural areas across Vietnam. They are often seen during the day, crawling around and hiding their wings similar to regular ants. When threatened, they react by expanding their abdomen and display aggressive behaviors like a scorpion. They can also fly and move quickly on land and water.

In addition to their bite causing painful burns and long-lasting scars, these ants secrete a toxic substance that can damage the skin upon contact. Their venom, Pederin, is 12-15 times more toxic than a cobra’s venom. Fortunately, the venom is not lethal to humans when it contacts the skin in small amounts. These insects are often found in rice fields, gardens, decaying grass, construction sites, and garbage dumps. They are most active during the rainy season and harvest times, often attracted to lights at night and entering homes after rain. If a stinging ant attaches to your skin, it is advised to gently blow it off rather than kill it with your hands.

Spiders, scientifically classified under the order Araneae, are predatory, invertebrate arthropods. Their bodies consist of two main parts: the cephalothorax and the abdomen, with eight legs and chelicerae that contain venom glands. Unlike the 150 species of spiders from families like Uloboridae, Holarchaeidae, and Mesothelae, most other spider species possess venom that they inject either for self-defense or to kill prey. However, only about 200 species have venom that is harmful to humans.

While most spider venom worldwide is highly dangerous and can be fatal, the venomous spiders in Vietnam are not as toxic as those found in other parts of the world. Victims bitten by venomous spiders typically experience swelling, inflammation, and pain. In more severe cases, symptoms may include allergic reactions, rashes, nausea, dizziness, and stomach pain, but these are not life-threatening. If bitten by a spider, it is advised to clean the wound with soap or disinfectant, apply a cold compress, and cover the bite with a clean bandage. Pain relief and anti-inflammatory medications may be taken as prescribed by a doctor.

Blood-Sucking Bedbugs range in size from 1- cm depending on their age, with a wide, flattened abdomen, smooth or short-haired head and body. The edges of their body have yellow stripes, and their characteristic brown color sets them apart from other bedbug species that come in a variety of colors like green, black, and brown. These bugs typically lay their eggs on furniture, beds, or in piles of firewood outside. The eggs are about 1-1.5 mm in size and have an off-white color.

These bedbugs feed on human or animal blood. If no animals are available, they will seek out humans. They can be found in various environments, from damp, dark areas to modern high-rise buildings. Commonly, they hide in mattresses, bedding, furniture, cracks in walls, or wood piles, making it hard to detect their presence during the day. They only come out to feed at night, which is why most people are unaware of their presence in their homes.

A bite from a blood-sucking bedbug is highly dangerous as it can transmit the intracellular parasite Trypanosoma cruzi, which causes Chagas disease. This illness leads to fatigue, drowsiness, and a weakened immune system. In more severe cases, the disease can cause blood vessel blockages and can be fatal when it becomes chronic.

The larvae of the Botfly pose a serious danger to humans. Once they enter and infest the body, they can travel anywhere, even reaching critical areas like the eyes, ears, and potentially crossing the blood-brain barrier, infecting the brain and leading to death. The affected area becomes swollen, pus-filled, and painful. After about 8 weeks of feeding, the larvae develop into pupae, create a hole in the skin, and crawl out. In cases of infestation in vital organs, surgery may be necessary to remove them.

Botfly larvae can enter the human body through an indirect route via blood-sucking insects. First, the female botfly lays its eggs on blood-feeding insects like mosquitoes, fleas, or bedbugs. When these insects bite livestock or humans, the eggs are transferred to the host.

Alternatively, the botfly can directly deposit its eggs onto the host's skin. The larvae hatch from the eggs and burrow under the skin, feeding on the host's nutrients until they mature.

The Lonomia caterpillars are the larvae of a type of moth. While they pose a significant threat to farmers, they can also be hazardous if accidentally touched. Although they do not have venom, suck blood, or bite, the spines of most Lonomia caterpillars release substances that cause severe skin irritation upon contact.

The spines can trigger intense pain in the affected skin, along with symptoms like hives and itching due to an allergic reaction. In severe cases, hemorrhagic spots may appear within 2-3 hours, or even after several days. Other symptoms can include swollen lymph nodes, fever, headaches, low blood pressure, and seizures. In extreme cases, severe allergic reactions can lead to death.

If you accidentally touch or get a Lonomia caterpillar on your skin, carefully remove it with a stick, brush off any spines if possible, then wash the area with soap or antiseptic solution, and apply cold compresses to reduce swelling and pain. Do not scratch the itching area as it could push the spines deeper into the skin, leading to prolonged and more dangerous symptoms.

The Aedes mosquito, scientifically known as Aedes aegypti, is the primary vector for dengue fever transmission in our country. However, many people are still unaware of the risks, the living habits, and the behaviors of this mosquito species that are directly linked to the spread of the disease. As a result, preventive measures are often inadequate or not fully implemented, leaving the risk of an outbreak a persistent concern.

Dengue fever is a dangerous disease with no specific treatment or vaccine available. It can escalate into a large-scale epidemic with numerous cases occurring simultaneously, making treatment difficult and increasing the risk of death, especially among children.

Aedes mosquitoes primarily live indoors and feed on human blood for survival. Their entire life cycle is closely tied to humans. These mosquitoes are constantly searching for hosts, but they are most active in the early morning and late afternoon. They only rest after feeding. Aedes mosquitoes typically bite people inside homes and prefer to rest indoors. It is rare to find these mosquitoes outside unless in humid forest areas. They are particularly attracted to dark-colored fabrics, such as woolen clothes and denim, as well as dirty clothes that haven’t been washed yet.

Fire ants are small reddish-yellow ants known for their painful stings. They are highly aggressive and can deliver a sharp sting that results in a blister after about 48 hours. These ants are a major pest in agriculture and urban areas, damaging crops and attacking both indoor and outdoor spaces.

Although fire ants are common in Vietnam, they are also responsible for approximately 80 deaths annually in the United States, with costs reaching $5 billion each year for medical treatment, property damage, and pest control. While the sting of a fire ant doesn't directly threaten life, it can cause excruciating, persistent pain. Additionally, the venom from some species of fire ants can lead to dizziness, shortness of breath, blurred vision, or even shock, depending on the individual's immune response.

If stung by a fire ant, it’s important to soothe the bite with soap and cold water, followed by an ice pack for about 10 minutes. If a blister forms, avoid popping it and instead gently apply a gauze to prevent the risk of infection.

Centipedes are long, segmented creatures with a pair of legs on each body segment. Their leg count varies greatly, ranging from under 20 to over 300 legs depending on the species. These animals typically live in dark, damp environments such as under floors, in drains, pipes, or even inside clothing. Adult centipedes are usually brownish-red or black. They are common in Vietnam, particularly in rural areas.

When a centipede bites, it injects venom through its two front fangs, causing the bite area to swell and become painful. For mild bites, a folk remedy involves applying chicken saliva to the wound. However, in more severe cases, symptoms may include vomiting and fever. If bitten by a large centipede with potent venom, the victim may experience dizziness, vomiting, ear ringing, and seizures, in which case immediate medical attention is necessary. Avoid rubbing the wound, as it could cause the venom to spread more quickly. The venom affects the nervous system, but it’s not lethal to humans, only paralyzing smaller insects.

There are 8,000 known species of centipedes globally, with 3,000 of them described. They are among the largest land-dwelling, predatory invertebrates and play a significant role in ecosystems by contributing to the biomass of land predators.

Scorpions are carnivorous arthropods with pincers. There are an estimated 2,000 scorpion species identified worldwide. In Vietnam, the most common species are the black and brown scorpions. The body of a scorpion is divided into two parts: the cephalothorax (front body segment) and the abdomen (rear segment). The tail section of the scorpion, which contains its stinger, is the primary weapon used to inject venom.

Most scorpion venom is not life-threatening to humans, but it can cause severe pain, swelling, numbness, and tissue necrosis. All scorpions possess a neurotoxin known as Chlorotoxin. Depending on the amount of venom injected, the duration of paralysis can vary. To reduce the danger of a scorpion sting, ice packs and pain-relief sprays can be applied to the wound, or painkillers containing Paracetamol can be taken. Particularly for children or individuals sensitive to stings, especially on the face, immediate medical attention and antivenom injections are necessary.

Scorpions are capable of regenerating lost limbs, and each species has distinct male and female individuals. Scorpions reproduce by transferring sperm from the male to the female. Scorpion offspring are born one by one and cling to their mother's back until they undergo at least one molt. Without this dependence on the mother, scorpion young cannot survive before their first molt. The maximum lifespan of a scorpion is not well known, but they can live anywhere from 4 to 25 years.

Hornets build open nests in trees, shrubs, or even in attics. When stung by a hornet, the severity of the reaction depends on the number of stings. Victims may experience anaphylactic shock, liver failure, blood clotting issues, kidney failure, or even death. The venom is contained in two venom glands near the stinger at the end of the hornet's abdomen. Upon stinging, the venom is quickly injected into the body. After being stung, it’s crucial to wash the sting site with soap or antiseptic and, if possible, remove the stinger using a clean tool. To reduce pain and swelling, apply a cold compress or ice pack for 15-20 minutes.

Healthcare professionals warn that hornet venom is extremely toxic and can cause serious damage to the skin, leaving scars, or even result in death. Therefore, after administering first aid, victims should drink plenty of fluids and be transported to a medical facility immediately. It is critical not to self-medicate with traditional, folk, or modern remedies, especially avoid applying lime to the sting, particularly when the sting is on the face, neck, or mouth.

In addition to their dangerous venom, hornets are fascinating creatures. Research has shown that hornets can accurately estimate time. Entomologists have observed them extending their tongues in a near-perfect rhythm, a skill that helps them gather nectar from flowers in nature.