Detouring around a hornet’s (Vespa affinis) nest in Mandai Besar mangrove

On a recce of Mandai mangrove and mudflats, I rounded a corner and froze. A hornet’s nest, holy cow! From my position I briefed my companions about the recommended reaction if they swarmed.

When I was in the army, a platoon-mate inadvertently disturbed a nest up a tree. That sent us scurrying and lobbing smoke grenades in a flash! These insects, however, were calm, so Joelle, Weiting and I chatted a bit while “Iceling” observed us somewhat nervously, wondering what to make of my “holy cow!” exclamation earlier. Her first trip to the tropics and all that. I had nly warned her about snakes, broken glass and mangrove whiprays, but the bit about moving slowly evidently covered scenarios like this!

After we had observed the hornets for some time, I decided a wide detour was appropriate since the soft ground could transmit vibrations to the nest – it was hanging off a fairly young tree. I could still remember my platoon-mate’s swollen neck when he returned from the hospital. Well, at least he didn’t need to do any more trench digging that day!

Vespa affinis nest, Sg Mandai Besar
The nest and a close-up. Hopefully Weiting’s camera did a better job!

This nest is not very high up a tree and could be easily disturbed by an unsuspecting researcher., especially someone focused on something on the ground or tree dbh! My first thought was of Rick Chin Leong and Dan Friess who frequent this area (and leave their untidy trademarks all over the mangrove). So from a respectable distance, I sent the google map placemaker to the blog, tweeted Dan and later emailed them both.

I remarked to Weiting, this is why we instruct Site Captains and Organisers to walk their site in the morning before participants turn up for the International Coastal Cleanup Singapore.

Kranji 2003 - pre-cleanup inspection
Conducting the pre-coastal cleanup dawn site inspection at Kranji in 2003 (photo by Charith Pelpola).

Hornet nest in Mandai Besar - 1.436344,103.761541 - Google Maps
Click for map

The hornets appeared to be the common Vespa affinis (lesser banded hornet) as the first two abdominal segments were yellow (see Chan, 1972. The hornets of Singapore: their identification and control. Singapore Medical Journal, 13(4): 178-197.

John Lee who maintains has lovely photos such as this one below:

John Lee: Lesser banded hornets (Vespa affinis) in Singapore :: 6 -- photo sharing network

He observes that “In Singapore, it can frequently be found on the beach, staying near rotting mussels which smell bad and attract flies. … they were simply creeping into the mussel shells and hiding there to ambush the flies!”

He also says, Vespa affinis is not particularly defensive near the nest so it possible to approach for observations. Then comes a big ‘however’ – “large numbers of workers will swarm out and attack pugnaciously when the nest is disturbed. ”

Oooh. Nice that we detoured!

Mandai Besar 24 May 2012
“Ice-Ling”, Weiting and Joelle – recce over and not a single swollen neck!

Oh well, otherwise, we’d make pretty impressive exhibits during the Festival of Biodiversity – all of us will be there, so join us at the Singapore Botanic Gardens, 26-27 May 2012!

To read more about John Lee and his work, see “Hooked on Hymenopterans!” Part 1 and Part 2 by Marcus Ng. Celebrating Singapore’s Diversity, 03 Feb 2010.


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