Four-spotted skimmer (see 08-16-13), eight-spotted skimmer, twelve-spotted skimmer . . there are several “skimmer” dragonflies whose colloquial names indicate the number of spots on their wings.
Last week hordes of eight-spotted skimmers (Libellula forensis) were flying at the McArthur Swamp near the Tule River (Shasta County CA), where these photographs of males were taken.
The eight-spotted skimmer is a medium to large dragonfly found west of the Rockies in North America. A resident of ponds and lakes, this dragonfly prefers water with a muddy bottom and weedy character.
Male eight-spotted skimmers are a brownish-black base color with a bluish pruinose abdomen showing tan or pink side spots. This pruinosity is caused by a bluish powdery covering that develops as the male matures. Females are not pruinose and have yellow, continuous (not broken as in the male) abdomen stripes. The face is dark brown-black. Each wing (of which there are four) has two dark spots with white in between. The stigmas (small, rectangular, colored, thickened areas of the wing on the front edge near the tip) are dark.
Eight-spotted skimmers eat soft-bodied flying insects such as mosquitoes, flies, butterflies, flying ants, flying termites and moths. Eight-spotted skimmer larvae (naiads or nymphs) live in submerged vegetation at the bottom of their pond or lake waiting for prey to pass rather than searching out their food.
After fertilization, the female eight-spotted skimmer lays its eggs by dipping her abdomen in shallow water while hovering above the water. Males do not fly with the females while they deposit their eggs, but often do stand guard while ovipositing occurs.
The number of spots on a skimmer dragonfly’s wings are determined by counting the dark spots (not including the stigma) on one wing and multiplying by four. Sometimes people count two spots (one on either side and touching the body) as a single spot because they appear to be “connected” across the body. Using this method an eight-spotted dragonfly would have six spots (four outer dark spots and two long spots over the body). Thus occasionally eight-spotted skimmers are referred to in the literature as six-spotted (and twelve-spotted skimmers as ten), but this is incorrect according to current custom.
I am delighted to have dragonflies and damselflies “flying” again, adding their color to the landscape.