Four-Spotted Skimmer and Twelve-Spotted Skimmer -Libellula quadrimaculata & Libellula pulchella
This blog's previous posts which highlight two different insects in the title are usually created in order to make comparisons between the two finds. Whether taken on the same day or a different day, together or separate, the photographed insects might be compared with regards to their behavior, appearance, predation strategies, defensive strategies, habitat, seasonality, or the possible ecological relationships between species. To be frank, these posts are also a good way to introduce small sets of pictures into a larger group and hopefully offer a good luck at some fascinating insects. However, the insects featured in such posts have always had a reasonable degree of separation - usually aiming to show specimens from different insect orders - in terms of taxonomy in order to keep things more varied. With this post, however, we will make an exception and highlight 2 larger Skimmer Dragonflies within the Libellula genus. As such, they are very closely related. It should be very straightforward which individual is which, but I realize while typing that this post doesn't include dorsal images of the Four-Spotted Skimmer. As such, you can review this post to see the dorsal side of this individual's wings and abdomen. As their names suggest, these Dragonflies can be easily distinguished from each other by looking at the number of spots on their wings, with the Twelve-Spotted Skimmer's spots being more prominent.
These two species also have notable differences in color, but they also share a commonality in the form of yellow striping running down their abdomens. This seems to be a particular common feature among members of the Libellula genus, especially in females and immature males. For the latter, many mature male Libellula species will gradually gain the waxy pruinose coating along their abdomen which will turn it white. Surprisingly, the Four-Spotted Skimmer is an exception to that, meaning that the adult Dragonflies mostly lack sexual dimorphism, which to me is a surprising finding within the Odonate order. Furthermore, while female and male Twelve-Spotted Skimmers will appear noticeably different while in the air thanks to abdomen color and the number of spots on their wings, Four-Spotted Skimmers will largely differ based on the abdomen's claspers (terminal appendages), and occasionally darker coloration on the female's stouter body. With regards to the former, the reduced and distanced claspers on the Twelve-Spotted Skimmer immediately tell us that this city-dweller individual is a female. Four-Spotted Skimmers actually don't follow the same rules; males and females both carry elongated claspers. However, thanks to the additional images, the near parallel claspers tell us that we have a female Four-Spot! While the diets and habitats (particularly near water) of these Dragonflies are bound to be similar to each other, with just a few observations we've noted that it insects within the same genus can be quite different in certain fundamental aspects.
Pictures were taken on May 24 & June 22, 2024 with a Google Pixel 4. These images would make a complete set if an Eight-Spotted Skimmer (L. forensis) could be shared here as well. Maybe next time, but until then, the Widow Skimmer (L. luctuosa) also covers much of the same ground.
