Sunday 9 September 2012: Wood wasp - no photo cropping required!
Well, in terms of photographing invertebrates for my blipfoto entries, I really hit a motherlode today! We stayed last night with our friends Ali & Dave outside Dumfries and went for a wander in a nearby woodland this morning. On a fallen conifer, we found not one but three wood wasps. Normally, I have to crop an insect photo to zoom in to show any detail but not with these babies. The largest of the three wood wasps was nearly 7cm long from tip to tip! Wood wasps are often described as fearsome looking and frequently are mistaken for hornets, people usually believing their extremely long ovipositor (egg laying structure) to be a massive sting! In reality, these huge relatives of wasps and bees (they belong in the sawfly family) are harmless and not to be feared (it's true)!
They lay their eggs in trunks of conifer trees, apparently dead or decaying. This tree today was a conifer that had snapped off at the base. The fact that three individual females all landed on it at the same time suggests it had reached an appropriate stage of decomposition for egg laying. You can see the thin black line of this wood wasp's ovipositor stuck vertically into the tree trunk as she lays her eggs. The long protective cover of the ovipositor is still extended out behind the insect (the hard structure being the reason for the wood wasp's alternative name of horntail). The larvae will live in the wood for up to four years, feeding on a fungus that is decaying the wood. The larvae, emerging as flying insects, carry the fungus out with them, introducing it into new tree trunks as the females, as here, lay their eggs. What a fantastic ecological relationship!
This wood wasp is, I suspect, the commonest species native to Britain, Urocerus gigas.