In a simplistic way, oil beetles have a very complex life cycle. The emergent female after mating lays thousands of eggs in an underground chamber. These hatch as minute larval clones of the adult. They then climb onto celandine flowers and wait for a passing insect. Any flying insect can be the vector, but only certain solitary mining bees can play host to the next stage of its life cycle. Anyway a flying insect lands on the flower, the larvae climb on board and are carried away.
If the flying insect is a solitary mining bee, they are taken into the bee's burrow where the larvae detach themselves, eat all the eggs of the bee, pupate and then emerge in a few weeks or the next spring, depending on the species. So a true parasitoid. This is a very simplistic synopsis as the life cycle is under researched, so John is learning as he studies them.
Eventually we found a black oil beetle too, which was fabulous as this meant 2 down 2 to go.
John has also been trying to discover the mating of these beetles and to do so has been collecting females and then introducing a male to them in a Tupperware box. All a little bit too voyeuristic really. But it is all legal as he's working on a research site and the beetles come from and are returned to the same area, hopefully to lay eggs successfully. The male in this photo (on right) grabs hold of the female by her antennae (which is why his are kinked so he can get a good hold), they have a tussle and then mate. The photo below was just after mating.
So after that excitement we headed down to the coast where at a secret location we found the short necked oil beetle, which for some reason I didn't photograph. That was three species found, just the rugged to go, which is known to be in this dry stone wall.
We looked and we searched but there wasn't any rugged oil beetles to be seen. Just too late in the year we think. We did however see a lot of common lizards which were taking advantage of the warm spring sunshine. Just goes to show if you stand still long enough, and look long enough, wildlife comes to you.
But the best was left to last. We'd been in the field for 7 hours and just about had enough energy to head back to the car. However John thought he'd seen some violet oil beetles making holes in a pathway last week and wanted to check if any were being used for egg laying. We hunted for about 20 minutes and then lo and behold, a female violet oil beetle was in the actual process of laying eggs. Just her head and one antennae were visible out of the soil, with her body completely buried. Absolutely fantastic to see this happening there and then. A great way to end an fabulous day in Devon.
Sadly not great photos as I still can't get my new Lumix to be pin sharp on the macro setting. I think it needs to be on a tripod. But there she is, egg laying with abandon.