The cost of long-horned moths long antennae?

As I walked past the university woodland area, in the usual clearing, a swarm of 7-8 Yellow-barred Long-horn moths, Nemophora degeerella in their bobbing flight. A few other males sat on the leaves facing the swarm. I searched for females to no avail, but something caught my eye, a male that had been caught in a spider web by his antennae (top shot), still alive, but kicking hopelessly. I have covered these moths in previous posts, the extraordinary antennae of their names only applies to males: the females have a much shorter antennae. This sexual dimorphism suggests that the male's antennae have evolved in response to sexual selection, possibly in relation to pheromone detection by males.

Two males rest on leaves (1/06/2017).

The evolution of exaggerated sexually-selected traits often is accompanied by costs and in the case of these moths, increased predation risk is a likely prize the males are paying for their oversized antennae.

A large swarm of long horned moths on 1/06/17.

Lekking long-horn moths

 In a walk by a wooded area on my way to work yesterday, I came across a few small swarms of dancing long-horn moths. I watched and waited until one of them sat to rest on the foliage: a Yellow-barred Long-horn moth, Nemophora degeerella. Long-horn moths are truly spectacular micromoths. Males are not only beautifully marked with metallic golden, chestnut and blue metallic stripes and a broad diagnostic yellow band across the wings, but their antennae are extremely long, several times their body length. It is astounding they can actually fly! Not only they can fly, but they perform a dancing flight, males bobbing up and down in a small area in shady wooded glades where they gather forming mating swarms or leks. These swarms, and possibly pheromones the males emit presumably serve to attract females and mate. Do females prefer males with longer antennae? These are day flying moths and I've watched the swarms in the morning or afternoon in warm sunny days in May and June. The antennae are white and so stand out as the moths fly. The antennae are strongly sexually dimorphic as the females, which I've never seen, are similar to males, but with short antennae. Their caterpillars feed on leaf litter.

 This is a short video of one of the moths appearing to sip honeydew from a leaf.

UPDATE 28/06/2017
A large swarm (over 20 moths) in the University Woodland area


via GIPHY