Late Summer Skimmers

The quiet waters of a pond like this make great dragonfly habitat

Dragonflies are conspicuous visitors to various bodies of water, especially in the warmer months of the year.    These visitors include members of the largest family of dragonflies, the Libellulidae, otherwise known as the skimmers. Skimmers can be large and colorful, some with distinctive wing patterns, and are often seen perching on twigs and branches.  In late summer, especially after summer rains, some locally common but not often observed species can be found around newly refilled ponds, including the Gray-waisted Skimmer (Cannaphila insularis), Needham’s Skimmer (Libellula needhami), and Slaty Skimmer (Libellula incesta).  

Found in shady or marshy ponds, typically with tall reeds or cattails, the male Gray-waisted Skimmer has greenish-blue eyes, a white face in front and metallic blue on top, and a dark brown or black thorax divided by several pale stripes.  Its abdomen is pruinose gray on the front half and black on the back half, and its wings are clear with extreme dark only at the tips.  Females and juveniles have a yellow-orange abdomen marked with dark brown or black.  Gray-waisted Skimmers are often found perching in the shade at the tips of vegetation, with their abdomen held nearly parallel to the perch.

Gray-waisted Skimmer, male

The male Needham’s Skimmer has reddish-orange eyes and face, and a thorax than is orange in front and paler or more tannish on the sides. Its abdomen is reddish-orange with a dark dorsal stripe down the length, and its orange wings are somewhat darker along the leading edge.  Females and juveniles have brown eyes and faces, a yellowish-brown thorax, and their abdomens are yellow with a dark stripe running down the middle.  Needham’s Skimmers are typically found perching low on vegetation or overhanging the water’s edge.

Needham's Skimmer, male

Most often seen around marshy forest ponds, the male Slaty Skimmer has dark eyes and a metallic blue or violet face, and both the thorax and abdomen have an overall slaty-blue pruinescence.  The wings are typically clear, but can have a pale bluish stripe along the leading edge.  Females and juveniles have red-over-gray eyes and a pale face, a cream-colored thorax with broad dark shoulder stripes, and a black abdomen with yellowish-orange markings. Females also have more prominent dark wing tips and develop a pale pruinosity at maturity.  Males perch on top of tall grasses and sticks most often in sunlit areas.

Slaty Skimmer, male

Check out your local pond or body of water before the end of September, and you just might be rewarded with a sighting of these less common, late summer skimmers!

A Killer of a Wasp

In late June and July, cicadas begin emerging from the ground,
breaking  through their shells or exuviae,
leaving the empty husks behind.

What are those large, solitary wasps we see flying around our yards from late June to September?  Often referred to as the Cicada Killer or Cicada Wasp (Sphecius speciosus), this native species occurs in the eastern and midwestern U.S. regions, southwards through Texas into Mexico and Central America. Cicada killers are so named since they prey on cicadas and provision their nests with them.  While large and intimidating, they offer a measure of natural control on cicada populations.  They benefit our native plants by pollinating flowers and protecting trees from the numerous cicadas that feed on their roots and foliage.

Cicada Killer or Cicada Wasp nectaring at a flower.

Cicada killers are robust wasps up to 2 inches long, with amber wings and black to reddish-brown abdomens with yellow stripes.  The females are somewhat larger than the males, and both are among the largest wasps in the U.S. These solitary wasps have a very unusual and interesting lifecycle.  Females are commonly seen skimming around areas with sparse vegetation for nesting sites, burrowing a tunnel, 10 to 20 inches deep, in dry or bare soil.  In digging a burrow, she will dislodge the soil with her jaws, and using her hind legs that are equipped with special spines, push the loose soil behind her as she backs out of the burrow. 

Cicadas, like this Megatibicen resh,
are hunted by the female Cicada Killers.

The female cicada killer proceeds to capture cicadas, sometimes even in flight, paralyzing them with her venomous sting.  She places the cicadas beneath her, grasping them with her legs, and either flies or drags her prey, which is twice her weight, into her burrow.  After placing a few cicadas in her nest, she begins to lay her eggs.  Females can predetermine the sex of the egg, and she lays multiple male eggs on a single cicada.  But each female egg is given 2 or 3 cicadas, as females are larger, require more food, and more females are needed to create new generations.  Eggs are always laid under the left or right second leg of the cicada. The female then closes the burrow with dirt, as the eggs hatch in a few days, but the larvae take some time to mature, feeding on cicadas as they overwinter in their burrow, not emerging as adults until the following spring.

Adult male cicada killers emerge in spring before the females, defending the territory around their emergence hole and searching for females.  They typically perch on the ground, flying up to attack any rival males. Once females emerge, mating occurs, and the males die shortly after.  Females live long enough to dig and provision their nests, and die after laying all of their eggs.

Cicada killer wasps are not aggressive toward humans and rarely sting unless provoked by grasping them roughly, accidentally stepping on them, or if caught in clothing.  Only the females have stingers, and while males will actively defend their perching areas against other males near nesting sites, they have no stingers. Both males and females have large jaws, but they are not known to grasp human skin and bite.  If swatted at, they will just fly away rather than attack. They are simply focused on cicadas or other cicada killers!