eTawau > Insects of Borneo > Wasps > A crown wasp at Bukit Gemok

A crown wasp on a fallen log

A female crown wasp, red-headed and needle-tailed, on dead wood beside the George Mais Trail at Bukit Gemok, in September 2008

She flew in, landed on a fallen dry log beside the trail, stood there for a couple of minutes while I photographed her, and flew off again. Black and slender, with long legs and a round, bright red head like a bead on a pin, she trailed behind her a single black thread longer than her whole body. That thread is her ovipositor, and it is the reason she was on a dead log.

A slender black wasp with a round, bright orange-red head standing on the grained surface of a fallen log, seen from the side, lit by flash against a dark forest background. Its long hind legs are thick at the thigh, its antennae are long and thin, and a very long black ovipositor runs back from the end of its body across the wood.
This is what you would see. The George Mais Trail, Bukit Gemok, 14 September 2008, 1.59 in the afternoon, by flash in the shade of the forest.

What she is

The same wasp, closer, with six labels: the ovipositor, longer than the body; the wings folded along the back; a narrow neck behind the head; the round red head; a long, thin antenna; and the swollen hind thigh.
The same frame, closer. Cropped and labelled; nothing else altered.

This is a crown wasp, family Stephanidae. The name comes from the head: it is almost round, set on a narrow neck, and on top it carries a small ring of bumps and teeth around the simple eyes, like a crown. Together with the head, three things mark the family:

The ovipositor makes her a female. Males are similar but have no ovipositor.

How far the name goes. Crown wasp, family Stephanidae, is safe. The family is small, with a few hundred species worldwide, but the genera and species are separated on the teeth of the crown, the sculpture of the neck and the veins of the wings, which these two photographs do not show clearly. The record has been posted to iNaturalist at family level.

Why she was on dead wood

Crown wasps are parasitoids of wood-boring beetle larvae. A female walks slowly over dead and dying wood, feeling and listening for a grub tunnelling inside. When she finds one, she drives her long ovipositor down through the wood and lays an egg on or beside it; her larva then feeds on the grub. A fallen log on a forest trail is exactly where she would be working, and the slow walk and short stay are typical.

The same wasp from above on the log, small in the frame: the red head, the black body and legs, and behind it the long black ovipositor lying along the wood, longer than the body.
From above, 1.56 pm, two and a half minutes earlier: the whole length of the ovipositor lying along the log behind her.

How big — not measured

There is nothing in the frames to give a scale, so this record has no size. The proportions can be read, though: the ovipositor is a little longer than the head and body together. Crown wasps in Borneo range from small to quite large; a female photographed for this site in 2016 measured 27 mm in body length, with an ovipositor of 32 mm — see the Wasps page.

Not dangerous. The ovipositor is for laying eggs in wood, not for stinging people. Leave her to work: a female crown wasp on a log is in the middle of finding a host for her young.

The record

14 September 2008 · 1.56 to 1.59 pm · on a fallen log

Standing on a fallen dry log beside the trail

The George Mais Trail (formerly the Gemok Hill Trail), Bukit Gemok Recreational Forest Park, Tawau, Sabah, 12 km from Tawau, measured from the 0 km Tawau landmark. One female, not measured, alone, standing on a fallen dry log; she flew in, stayed a few minutes and flew off. Round orange-red head on a narrow neck; black, slender body; long, thin antennae; hind thighs swollen; ovipositor longer than the body. Hymenoptera: Stephanidae — a crown wasp. Genus and species not determined. Two frames, by flash, 13:56:49 and 13:59:15.
— iNaturalist observation 404863478

The same day

Two hours earlier, on the forest floor of the same hill, the same walk produced a pair of flat-backed millipedes mating, and the day also turned up the great winged seed of the climbing gourd Alsomitra macrocarpa, described on the Bukit Gemok page.

Words you may meet

Stephanidae
The crown wasps, from the Greek for "crown".
Ovipositor
The egg-laying tube of a female insect.
Parasitoid
An insect whose larva feeds on a single host and kills it, unlike a parasite, which usually lets its host live.
Femur
The thigh, the thickest segment of an insect's leg.

Related pages

About the photographs. Two frames by Wong Fook Yee with a Canon PowerShot A460, by flash, at 13:56:49 and 13:59:15 on 14 September 2008 on the George Mais Trail at Bukit Gemok, Tawau, Sabah. Both files had been saved through Adobe Photoshop 7.0 at full camera size, the first turned upright. For this page they have been reduced, and one cropped and labelled; nothing has been sharpened, recoloured, added or removed.

The account of crown wasp biology is from the general entomological literature. The locality, date and behaviour are the photographer's own. All photographs © Wong Fook Yee. Page written 1 October 2026.