Low-light conditions, a bit blurred. Was fascinating to see, as it iterated over multiple target apids and stabbed them all. Aphids didn't even attempt to run. Interestingly, only chose small aphids, even a very small one (seen in this photo at the lower left, near the posterior tip of the wing of the wasp).
Another unusual insect: Tenthredo baetica (ssp. dominiquei), with only 118 observations world wide, of which 29 for this particular subspecies. It's a wasp – sort of: a sawfly.
The rear limbs are rather large, and I wonder why. For carrying prey?
Wikipedia points out an interesting reversal: in the Tenthredo genus, the larvae eat plants while the adults prey on other insects. Whereas many typical wasps do the opposite: the adults sip nectar but hunt insects to feed their young. https://en.wikipedia.org/wiki/Tenthredo One wonders then what is this adult doing on a flower, engaging in motion patterns characteristic of foraging on nectar and pollen.
Some wasps are called 'parasitoids' because they lay their eggs in still-living caterpillars. The eggs develop into larvae that eat the caterpillar from the inside.
But turnabout is fair play. Sometimes, other wasps called 'hyperparasitoids' lay their eggs in the larvae of these parasitoids!
The caterpillars also fight back. Their immune system detects the wasp's eggs, and they will do things like surround the eggs in a layer of tissue that chokes them.
But many parasitoid wasps have a trick to stop this. They deploy viruses that infect the caterpillar and affect its behavior in various ways - for example, slowing its immune response to the implanted eggs.
These viruses can become so deeply symbiotic with the wasps that their genetic code becomes part of the wasp's DNA. So every wasp comes born with the ability to produce these viruses. They're called 'polydnaviruses'.
In fact some wasps are symbiotic with two kinds of virus. One kind, on its own, would quickly kill the caterpillar - not good for the wasp. The other kind keeps the first kind under control.
And I'm immensely simplifying things here. There are over 25,000 species of parasitoid wasps, so there's a huge variety of things that happen, which scientists are just starting to understand! I had fun reading this:
Why such diversity? I think it's just that there are so many plants! So insect larvae like caterpillars naturally tend to feed on them... in turn providing a big food source for parasitoids, and so on.
Given that pretty much all insect species, and beyond into spiders and more, are attacked by parasitoid wasps, and that for most hosts there are both host-specific and generic parasitoid wasp species, it’s been estimated that there are more parasitoid wasps than all other insect species combined. Their usually cryptic larval life stages and often brief adult stages may be behind the severe undercounting.
See:
"Quantifying the unquantifiable: why Hymenoptera, not Coleoptera, is the most speciose animal order", Forbes et al. 2018 https://doi.org/10.1186/s12898-018-0176-x
... competing with wing loss in flies (flightlessness), at 25 events counted to date. Can't find an up to date citation; a neat phylogenetic tree of #Diptera marking all the apomorphic events was shown to me by Darren Williams. There's Wagner & Liebherr 1992 https://www.sciencedirect.com/science/article/abs/pii/016953479290047F listing 22 insect orders with flightless species: almost all of them have species with secondary wing loss.
My favorite wingless insect is not a fly but a whole family of wasps: the velvet ants. Here, an American one. Note only females are wingless. The power of their sting is also the stuff of legend.
X-ray microscopy of fossil parasitoid wasps to study the evolution of echolocation for finding hosts:
"†Kryptovelona carstengroehni gen. et sp. nov. and †Orussus juttagroehnae sp. nov. are the first female members of the parasitoid wasp family Orussidae recorded from Baltic amber. We describe them, including relevant parts of the internal anatomy examined with synchrotron scanning. The fossils display a number of modifications in the antennae and foreleg correlated with the specialized host-detection mechanism, and in the ovipositor apparatus, as well as in the thorax and abdomen for accommodating the internalized ovipositor."
"By comparing the new Baltic amber taxa with †Cretorussus, it is possible to trace the progressive refinement of the echolocation mechanism through reductions in the number of antennomeres and foreleg tarsomeres."
Large body size differences across species in Hymenoptera. Here, an example of a small masked bee (~7 mm) next to a minute ant (<3 mm) on a flower of European sea rocket (Cakile maritima). https://www.inaturalist.org/observations/120155371
And these two are both tiny next to a violet carpenter bee (Xylocopa violacea), measuring well over 40 mm in body length! https://www.inaturalist.org/observations/178658335 Similarly dramatic size differences exist within ant castes of the same species.
Wondering here out loud whether these vast differences in body size relate, at least metabolically, to the ability of hemimetabolous insects to hatch from the egg as tiny miniature versions of the adult, and then grow by moulting multiple times. I mean they must relate. These incremental steps, hormonally regulated, surely afford opportunities for evolution to meddle and trigger sexual maturation which, in needing to reallocate resources to reproduction, would concomitantly stop body growth. And it's true that smaller insects moult less times, and that moulting renders the animal helpless (and subject to e.g., predation by hornets: see this poor Mediterranean locust, Anacridium aegyptium https://www.inaturalist.org/observations/91574142 ) for tens of minutes if not more.
@friesen5000 Some wasps drill through hardened, dried out wood in search of beetle larvae to stab and "entrust" with their offspring... a Petri dish, with its thin wobbly soft plastic walls, seems small potatoes for a parasitoid wasp!
Most impressive is that Eupelmus messene measures only 2-3 millimeters. #wasplove
Pteromalidae, one of my favourite wasp families—and one that I can never identify to the species. Small and metallic looking, these parasitic wasps love hanging around recently pollinated flowers in search of insect eggs or larvae onto whom to entrust their offspring. I’ve chased this tiny wasp across flowers, dry and green grass twigs, and leaves; mostly prefers short flights, more like hopping about. http://www.inaturalist.org/observations/181792448
A Pteromalidae parasitoid wasp sits still next to a ground crab spider, Xysticus sp. Thanks to Adriano Cazzuoli at #iNaturalist am now alerted to the possibility that this wasp is a parasite of the spider’s eggs. To top it off, the spider has predated upon a smaller wasp of similar colouration, Pteromalidae-like in shape, and is holding on its jaws; and between there’s a whitish maggot or pupa of perhaps a small hymenopteran.
Um yeah... crazy huge colorful flea beetle (Aspicela scutata). Whoever said blue is hard to find in nature didn't study tropical insects. I am really curious though if this is a refraction trick or if this is actual pigmentation. I presume its the latter.
Velvet ants are solitary wasps with hardened exoskeletons and often very powerful and painful venom; they hunt viciously, accumulating paralised prey in burrows where they lay their eggs. The hatching larvae will eat the prey alive.
This one showed herself a great digger. Dug multiple times, a few seconds at a time, as if looking for something. How bees and wasps manage to dig so effectively never ceases to amuse me.