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The last pic looks like a small Platypalpus (Hybotidae), and it's interesting to see that both male and female culicids are apparently feeding on the flowers (female mosquitoes don't just eat blood). There are indeed several chironomids present, though none have pollen on them, and most seem uninterested in the flowers - perhaps they were just resting on convenient vegetation? These Echinocystis flowers look like they have readily available nectar - the lower Dilophus picture shows this well, I think - so it may be that some of the chironomids could feed on it, but this would be unusual behaviour for them.