Dragonfly or Damselfly?Side by Side The Little and Large Show The Shell Game Going to Extremes Side by Side answer Going Zen The Rule Acknowledgement of sources
Author Jeff Melvaine ◦
Quiz 1: Side by Side answer
Southern Vicetail (Hemigomphus gouldii) male and Arrowhead Rockmaster
(Diphlebia nymphoides) male, Gloucester River, Invergordon NSW
By now, the two species above may look familiar to you. The one on the left is a Southern Vicetail (Hemigomphus gouldii) male, very (and often confusingly) similar to the mature Stout Vicetail male from Tallebudgera Creek. The one on the right is an Arrowhead Rockmaster (Diphlebia nymphoides) male, and this is exactly the species you saw before in copula at Ebor. So you now know that the damselfly is the one on the right. Paradoxically, given that it is bigger and heavier, and is holding its wings open, but there are some clues in this photo, apart from prior knowledge.
The first clues are in the terminal appendages, if your device has sufficient resolution to show them; I would recommend a laptop screen at the least. The Vicetail has two large pale cerci at the end of its abdomen, and a single long dark epiproct below them: dragonfly. The Rockmaster has two long curved cerci at the end of its abdomen, and two short square paraprocts just visible between them: damselfly. (As mentioned above, there are some non-Australian species for which the first part of that rule is wrong or at least misleading.)
A clue with rather better long-range visibility is in the eyes. Those of the Vicetail are not shown from the necessary perspective here, but you know there is only one damselfly in this image, and the face of the Rockmaster is front on in this view. Its eyes are separated by more than their individual width; they are sideways facing. Also, it is clear in this view that the Rockmaster’s wings have long narrow stalks at the base. So on that basis you can be confident that the Rockmaster is the damselfly.
Dragonfly or Damselfly?Side by Side The Little and Large Show The Shell Game Going to Extremes Side by Side answer Going Zen The Rule Acknowledgement of sources
Footnote & References
- Author Jeff Melvaine / Photographs © Jeff Melvaine
Dragonflies & DamselfliesDragonfly or Damselfly? Sex Lives and Dragonflies Damselflies Diplacodes haematodes Hemicordulia tau Orthetrum caledonicum Orthetrum migratum Orthetrum villosovittatum
InsectsBees Beetles Blattodea Butterflies Coleoptera Cicada Crabronidae Diptera Dragonflies & Damselflies Formicidae Hemiptera Heteroptera (True Bugs) Mango Planthopper Moths Orthoptera Orthopteroid Processionary Caterpillar Stink Bugs, Shield Bugs and Allies Syrphidae Wasps Water Scorpion (Laccotrephes tristis) Witchetty Grub