An expert explains what we really need to understand about these & # 39; killer hornets & # 39;

According to recent press reports, two giant Asian hornets, an unknown species in North America, were found in northwest Washington State in late 2019, and a colony of hornets was found and eliminated in British Columbia.

Scientists are now trying to determine if there are more of these large predatory insects in the area. Entomologist Akito Kawahara explains why the titles refer to "hornets murder"they are deceiving.

1. How common are these hornets in Asia and how alarming are they?

The Asian giant hornet (Vespa mandarinia) is quite common in many parts of Asia, where it is called "giant hornet". Growing up in Japan, I saw them quite frequently in the mountains outside of Tokyo.

These insects are large and distinctive, with a characteristic orange head and an orange body with black bands. Like any other social wasp, they will defend their nest if the colony is disturbed. But in most cases, they will do nothing if people are not aggressive towards them.

Giant hornets have longer prickles than those of a bee, and hornets do not break their prickles when they bite. Because hornet stings can pierce thick clothing, people should avoid hornets and their nests as much as possible.

Giant hornets are often attracted to tree sap – a bit like me when I was looking for butterflies in trees. The bite is painful, but the swelling and pain in most cases decreases within a few days.

As with bee stings, an allergic reaction or anaphylaxis can sometimes lead people to the hospital. In some cases, severe reactions can become fatal. But wasp and hornet stings were killed less than 13 people per year in 2017 and 2018 in Japan – less than 0.00001 percent of the national population – in a country where many people spend time in the forest.

If you are allergic to bee and wasp stings, it is best to avoid getting close to these insects and their nests, to wear white clothes outside (they are attracted to dark colors) and avoid carrying open sugary drinks like soda in the woods.

2. Are you surprised that hornets have appeared in North America?

To a certain extent, yes. There is a good chance that a single fertile hornet entered Canada via shipping packages and created the colony discovered in 2019.

It is easy for invasive species to travel this way. Over 19,000 freight containers. arrive daily in American ports USA

and inspectors can only perform random searches for shipping containers. An estimate suggests that 2 percent of shipments The search for pests such as plant pests is sought. Many invasive species are intercepted, but some do.

It is highly unlikely that an entire colony of hornets was transferred to North America. The colonies of this hornet are often large and the hornets would be visible and potentially aggressive if their nest were disturbed.

Genetic tests indicated that one of the hornets found in Washington was unrelated to the Canadian colonyBut these results have not been published or peer reviewed. The giant hornet was not found either in 2020 or in the United States. USA Not in Canada.

(Gailhampshire (top left), Gilles Gonthier (top right), Judy Gallagher (bottom images), all via Flickr, CC BY)

Sure: Four species of wasps and hornets are often confused with the giant hornet. Top left: European hornet (Vespa crabro) Top right: common aerial yellow jacket (Dolichovespula arenaria) Bottom left: European wasp (Polistes dominula) Bottom right: bald hornet (Dolichovespula maculata)

3. What conditions do these insects need to live?

Giant hornets are quite common in the mountainous regions of Asia, but are often not seen in large cities or highly urbanized areas. They generally nest at the foot of large trees and in dead trunks. The fact that they cannot tolerate extremely high temperatures cold temperatures

it is unlikely to spread in the very hot or cold regions of North America.

If active colonies are discovered in 2020 in the Pacific Northwest, which has a milder climate, they can spread there. However, this is unlikely to happen quickly since the feeding ranges of Vespa they are alone about 2,300 feet (700 meters) from its nest.

The key to preventing spread is surveillance. Anyone in the Pacific Northwest should be alert to giant hornets when outside this summer and fall.

4. If more hornets are found, could they threaten bees and other pollinators?

Perhaps. Some media reports have described the destruction of honeycombs for what could have been giant hornets, but bees are not the only prey for these insects. Hornets feed on different types of insects and carry dead prey captured in their hive to feed their young.

In Japan, beekeepers surround their hives with mesh netting to protect them from hornets. North American beekeepers can reproduce them with metal nets at local hardware stores.

Many bees in Asia have the capacity to protect their hive from intrusions of giant hornets burn them. They wait for a hornet to enter their nest, then completely surround it with their bodies.

Each bee vibrates its wings, and the combined heating of the bee body raises the temperature in the center of the cluster to 122 degrees F (50 degrees C), killing the hornet. Carbon dioxide levels in the nest also increase during this process, contributing to the death of the hornet.

5. Is the news about "murderous hornets" exaggerated?

Yes a lot like that. In some parts of Japan, people see these hornets as beneficial because they kill pests, such as pests, from crops. They are also believed to contain nutrients and have been used as ingredients in Japanese food and some strong spirits. Some people believe that the essence of hornets has medicinal benefits.

People living in Vancouver, Seattle or the surrounding area should take note of what these insects are. They measure 2 inches or more, with a 3 inch wingspan, and have distinctly large orange heads and abdomens with large black stripes. It is different from typical North American hornets, which have yellow or white bodies with black markings.

In the unlikely event that you see a giant hornet in Washington State, don't try to remove the nests yourself or spray hornets with pesticides. Cutting down trees to avoid nesting sites is also unnecessary and can affect many other types of native wild animals, including beneficial insects necessary for pollination and decomposition. Many native insects are global decline, and it is important to make sure that these insects are not affected.