足長蜂: to exterminate or not?

I need some practical advice. Recently, we have found some uninvited guests on our balcony: a small colony of 足長蜂 (ashinaga-bachi, paper wasps) industriously building their hive right under our roof.

While our first instinct was to declare war on the intruders and launch a biological attack of unprecedented scale, our daily observations made us refrain from such drastic steps. You may even say we have grown quite fond of them and do seek peaceful co-existence. Still, we exercise utmost caution when hanging up the laundry.

WikiPedia states:

Unlike yellowjackets and hornets, which can be very aggressive, polistine paper wasps will generally only attack if they themselves or their nest are threatened. Since their territoriality can lead to attacks on people, and because their stings are quite painful and can produce a potentially fatal anaphylactic reaction in some individuals, nests in human-inhabited areas may present an unacceptable hazard.

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Can anyone share valuable information on the issue? How long is a wasp-hive usually inhabited? Would you just go ahead and ruthlessly exterminate?

I do not have any experience with 足長蜂, but according to internet sources, they start building their hive around April and by the winter they all die out. Old hives will never be used once their inhabitant are gone, and the chance a new hive will be built in the same place is small.

As you've already checked out, they won't attack people as far as they are not disturbed, and because they catch catepillars and worms, they are regarded as beneficial insects, especially by those who enjoy gardening.

What would I do if I have 足長蜂 in my balcony?
It depends where exactly in the balcony the hive is built - I'd leave them alone unless our paths could cross far too often in everyday life.

undrentide said:

What would I do if I have 足長蜂 in my balcony? It depends where exactly in the balcony the hive is built - I'd leave them alone unless our paths could cross far too often in everyday life.

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My thoughts exactly. Thanks for your advice.

Just a little update: after one week of more or less peaceful co-existence - by maintaining as much distance to them as possible - the queen finally left the hive, prompting the wasps to swarm all over the balcony. Our guests had clearly turned into intruders and were no longer welcome.

We attacked under favour of night using a "toxic wasp gun":


With an effective range of up to 10(!) metres and a firepower of 45secs of continuous spraying quite efficient, yet horrible to witness. The next morning we had a few hornets patrolling the battlefield, obviously preying on the deserted hive. They shared the same fate.

Seems to be a common problem in Japan though, here's another blog entry on the subject, just in case any of our members suffer from those long-legged critters.