Sierra Dome Spiders, Neriene litigiosa, build sheet webs more or less in the shape of a dome with an internal flat web. The female, about 7 mm long excluding the legs, hangs upside down in the peak of the dome waiting for prey. The silk in these webs is so fine that they’re nearly invisible except when covered with dew.
1: female, 2: male, 3: male and female, 5 and 6: single web from two perspectives
In at least some circumstancefor example in very sparce populationsfemales deposit a pheremone on their webs to attract males. A male may remove the pheremone after mating to prevent other males from being attracted. (See “The Case of the Missing Perfume” on The Animal Communication Project)
Seirra Dome Spiders on bugguide.net