According to experts on the BugGuide Facebook group, the spider is probably an unknown species from the Family Araneidae (Orb Weavers).
Post Update:Ashley Bradford, a local arachnid expert and excellent all-around amateur naturalist, identified the spider as an Arabesque Orbweaver (Neoscona arabesca). Thanks, Ashley!
Aperture Priority mode was used for the next photo, in order to increase the depth of field. As you can see, the depth of field at f/8.0 was insufficient for both the damselfly and spider to be in focus.
Copulation brief (averages 20 sec) and aerial, may be followed by resting period. Source Credit: Paulson, Dennis (2011-12-19). Dragonflies and Damselflies of the East (Princeton Field Guides) (Kindle Location 10228). Princeton University Press. Kindle Edition.
The mating pair was in wheel when they landed. I was able to shoot one photo before they finished copulating!
The photos in this set were taken on a very windy day. The wind was blowing so hard the dragonfly struggled to hold onto her perch, as shown in the next photo when the pennant was almost flipped upside-down.
Chiggers and ticks parasitize human odonate-hunters sometimes; water mites parasitize odonates sometimes. In my experience, some species of dragonflies seem to be more likely to be infested with water mites than others.
Lentic, slow moving water, ponds and temporary water are what mites need for their life cycle. The mites get onto late stage [odonate] nymphs, and then emerge with the nymph. As it ecloses the mites transfer to the adult damselfly, dragonfly. Life cycles of mite and host must be at stages where this can happen, so only certain species would probably be emerging at those times. Species that emerge earlier or later in the season probably wouldn’t have to deal with them. There’s more than one species of mite, so different species would emerge at different times. There is some reference in Corbet’s book [Corbet, Phillip S. (1962). A Biology of Dragonflies.] about some (grooming) species grooming themselves better, and knocking them off also, so they’ve evolved to attach to species where their life cycle can be completed. Some of these species disperse them well also. Nature is truly amazing! Source Credit: Stick LaPan, Northeast Odonata Facebook group.
Odonates and parasitic water mites are able to co-exist except in cases of extreme infestation, when parasitization can be fatal.
Another Halloween Pennant dragonfly, spotted at the same remote location 12 days earlier, has an infestation of red water mites. This individual is an immature male, as indicated by its coloration (similar to a female) and terminal appendages.
A Blue Dasher dragonfly (Pachydiplax longipennis), spotted along the boardwalk in the central wetland area at Huntley Meadows Park, has an infestation of black water mites. This individual is a male, as indicated by its blue coloration and terminal appendages. He is perching in the obelisk position, thought to be a method of thermoregulation.
Turns out the growth is a gall caused by a parasitic wasp. Charley Eiseman, widely regarded as the go-to gall guy, said “It is likely a Diplolepis sp. gall.” Diplolepis is a genus of gall wasp in the Family Cynipidae.
Charley also said the only way to make a positive identification would be to collect a few galls in the hope of capturing some wasps when they emerged from the galls. In the interest of science, Kevin Munroe, manager at Huntley Meadows Park, kindly granted one-time permission for me to collect a few galls.
Waiting and watching
On 11 March 2014, three (3) insect galls — similar to one I photographed during Fall 2013 — were collected from Swamp Rose (Rosa palustris) plants located alongside the boardwalk in the hemi-marsh at Huntley Meadows Park. The largest gall was ~1.9 cm (~3/4 in) long. There was one small hole in the gall when it was collected; there were no holes in the other two galls.
The galls were stored indoors in a sealed Ziploc plastic bag for several weeks. I checked daily to see whether anything had emerged. At least once, moisture was wiped from inside the bag in order to prevent the galls from getting moldy.
04 April 2014
The following photograph is shown for scale: the insect galls (and later, tiny gall wasps) were stored in a Johnson Ziploc XL Sandwich bag; its dimensions are 7 in x 8 in (17.7 cm x 20.3 cm). I taped the plastic bag to the window of my apartment at the Beacon of Groveton in order to shoot still photos and video before sending the specimens to Charley Eiseman.
04 April 2014
Gall wasps began emerging from the galls on 03 April 2014. The preceding photos were shot on 04 April 2014, and the following movie was recorded on the same day. Individual specimens are ~2 mm (1/16 in) long.
Tech Tip: The preceding video looks better viewed in full-screen mode.
A closer look at what emerged from the galls
Charley Eiseman used a Canon EOS Rebel XSi, MP-E 65mm lens, and MT-24EX Twin Lite flash to shoot the following excellent macro photographs on 08 April 2014.
The first photo shows a gall wasp (~2.2 mm long) that was covered with “crumbs” from chewing its way out of the gall.
One parasitoid, shown below, emerged among tens of gall wasps: Eupelmus dryohizoxeni (female), 3 mm long. That’s right, this parasitoid feeds on the gall wasps that parasitize Swamp Rose — now there’s an interesting and unusual food chain!
The gall wasps collected at Huntley Meadows Park don’t seem to match any species in the scientific literature, so Charley Eiseman sent some specimens to an entomologist who specializes in micro-wasps. We are waiting patiently for the specialist to identify the species.
Editor’s Notes: Sincere thanks to Kevin Munroe for facilitating my amateur scientific investigation, and to Charley Eiseman for his extraordinary kindness in helping a virtual stranger!
The following photographs show a Blue Dasher dragonfly (Pachydiplax longipennis) spotted along the boardwalk in the central wetland area at Huntley Meadows Park. This individual is a male, as indicated by its blue coloration and the terminal appendages at the end of its abdomen.
Male dragonflies have three terminal appendages, called “claspers,” including a pair of upper appendages called “cerci” and one lower appendage called an “epiproct.” The Blue Dasher’s cerci are black and are visible in all photos; its epiproct is tan and is visible in Photos 3-4. The male dragonfly’s claspers are used to grab and hold female dragonflies during mating.
The black nodules on the underside of the dragonfly’s thorax, shown clearly in Photo 1, are parasitic water mites.
Water mites (Family Arrenuridae) are a common still-water odonate parasite. They hatch from eggs laid underwater and the larva are free swimming. They seek then attach themselves to odonate larva and when the odonate larva emerges to molt into an adult, the mites transfer to the teneral dragonfly or damselfly. The mites continue to feed on the odonate’s fluids while the dragonfly/damselfly matures. When the odonate returns to water to reproduce, the mites drop back into the water where they continue to develop, undergoing a series of molts, feed on other underwater creatures, mate, and lay eggs. Source Credit: Ed Lam, author and illustrator of Damselflies of the Northeast.
Some dragonflies, such as Blue Dasher, regulate their body temperature by perching in the “obelisk position”: the tip of the dragonfly’s abdomen is pointed toward the Sun, minimizing the surface area of the body exposed to direct heating by the Sun’s rays, thereby avoiding overheating.
