I came across this magnificent spider wasp (Pompilidae) feeding on nectar from these flowers beside the steps leading up to Wat Tham Pha Plong, Chiang Dao, Thailand. I have come across this pompilid wasp before in northern Thailand (1), but I am still not sure what species it is. With its orange antennae, it looks similar to the Australian orange spider wasp (Cryptocheilus bicolor) (2), but the head is not orange and the abdomen is black. So perhaps it is another Cryptocheilus species, of which there are twenty-four known. One website provides a check-list of pompilid species from Thailand (3), but none of these seem to fit the bill. Other sites, simply caption photos ‘Pompilidae’, so it is not one that can be identified from of the Internet. If there are any pompilid experts out there, I would love to know what it is!
Adult pompilid wasps feed on nectar, but they hunt and kill spiders to provide a food source for their off-spring. They sting and paralyse spiders and carry them off to a nest burrow, where they deposit an egg on the hapless arachnid. Each offspring has its own spider to gorge on. The wasp larva hatches out and starts feeding on the living, paralyzed spider. The bigger the spider, the more likely it is that the larvae will develop into a female wasp (which are larger than males).
I would think that there is much to learn about these wasps, particularly species which have been little studied. The are nearly all solitary wasps although a few communal, mud-nesting species exist (4). The hunting behaviour of one group of pompilids, the tarantula hawk wasps – which occur in the deserts of the USA – has been studied: “the wasp rushes at the spider, grabs a leg, flips the spider onto its back, and stings it….” The tarantulas can mount a counter attack, but it seems they are at a disadvantage and rarely succeed in killing the attacking wasp. (5) One can only wonder at how long this evolutionary battle between wasps and spiders has played out over geological time.
Some pompilid wasps are cleptoparasitoids; they steal the spider prey caught by other pompilid species. They wait until the wasp which has caught the spider puts it down and turns its attention to nest making; they then rush in and lay their own egg on the spider. This egg hatches out before the one laid by the wasp which first caught the spider, and the imposter larva eats the host egg before it hatches. (5) Very sneaky!
Some pompilids prey on species such as this orb spider, Argiope pulchella (6). The spider is sitting in the middle of an X-shaped stabilimentum; an elaborate web decoration or feature which it has constructed out of silk (below).
I don’t know how poisonous the sting of this particular wasp I photographed would be to humans; and I would not like to find out.
Pompilids are not aggressive and are usually relatively docile (unless provoked), but the sting of the closely related Tarantula hawk wasps is reportedly very intense. The pain has been described as: “like an electric wand that hits you, inducing an immediate, excruciating pain that simply shuts down one’s ability to do anything, except, perhaps, scream.” (7)
One has to admire the skill and tenacity of these wasps, which often prey on spiders which are much larger than themselves, and highly venomous. They have evolved a way of exploiting this prey source and presumably play an important role in regulating spider populations.
Butterflies, like this Clipper (Parthenos sylvia) also enjoy feeding on the flowers of this plant.
- O’Neill, K. M. (2001). Solitary wasps: behavior and natural history. Cornell University Press.