Flower wasps: an intriguing mating ritual

Flower wasps: an intriguing mating ritual

Mating insects are a common sight in Spring and Summer. There are the piggy-backing beetles, neck-grasping dragonflies and end-to-end crane flies, for example. 


But this morning two wasps created an entirely new spectacle for us.


The twisting, thrashing abdomen of a small, black wasp caught my attention. It was perched on a sedge leaf, head down, waving its rather bulbous-tipped body in the air. A closer look revealed that the 'bulb' was actually the much smaller, wingless female. 

These really are quite small insects. I measured the leaf ... it is only 3mm wide!


Over several minutes, as I looked on, the male continually waved the tip of his abdomen. He would occasionally also spin on the spot, or move a short distance along the leaf. The female was also wriggling, sometimes stretching out and reaching with her jaws wide. Most of the time, however, she remained curled over. 

Then, quite suddenly, he flew to a nearby flower head ... and they parted.


The male immediately flew off while the tiny female crawled down to the ground and disappeared among the leaf litter.


So, what was going on here? What is known about flower wasps? Quite a lot, I now realise after a day trawling books and online. There are numerous descriptions of flower wasp mating behaviour, although the information on the specific biology of individual species is much more limited. 

Flightless females

There are estimated to be around 715 Australian species of flower wasps (Order: Hymenoptera; Family: Tiphiidae) belonging to the large subfamily Thynninae. The females of most species lack wings. They release species-specific pheromones to attract males and then are dependant on the male for food.

Nuptial gifts

Males usually provide nectar for the female during their somewhat protracted coupling. In some species, he carries her to flowers where they both feed. In others, the male will prepare a sugary droplet as a 'nuptial gift'. She may take it from him directly, or he may place it on a leaf and then reposition himself such that she can take it. I suspect this is what I was seeing this morning, when the male would spin in place and move slightly along the leaf, and the female would reach out with her jaws extended.

Parasitic larvae

The adults are flower feeders but their young are strict carnivores. Eggs are laid on subterranean beetle larvae. The wasp larvae devour their host and then pupate underground, emerging only once they eclose as adult wasps.

Species identification is not simple

The taxonomic descriptions for Tiphiidae are patchy, so I'm not even going to try. This pair belongs to the subfamily of Thynninae, but beyond that, who knows? The species may not even be a described one. It is estimated that only one in five Australian hymenopteran species (bees, wasps and ants) have been scientifically named!

If I start looking more closely, I'm sure I'll discover dozens more wasp species here in the forest. But for now, I really must get back to my latest collection of bee photos. I'm starting to get a feel for the different types of feeding strategies different bee species employ, and the different types of flowers they visit. But more about that in my next post.