If the wings of butterflies are famous for their beautiful colors, similar to those of impressionist paintings, the wings of the 𝘕𝘦𝘶𝘳𝘰𝘱𝘵𝘦𝘳𝘢 insect order resemble more like fine dentelle. You may have heard about these insects under the names of antlions, mantidflies, owlflies or lacewings. Our focus today is actually on a genus of common green lacewings, 𝘊𝘩𝘳𝘺𝘴𝘰𝘱𝘦𝘳𝘭𝘢. Species of this genus possess two pairs of transparent and thin wings with a complex network of veins and to date over 60 species have been described, with those being particularly common in North America and Europe.
The diversity of 𝘊𝘩𝘳𝘺𝘴𝘰𝘱𝘦𝘳𝘭𝘢 in these regions may be more important than previously thought, in particular for what is known as cryptic diversity. Traditionally, scientists have been separating species based on their morphology, with the idea that different species should look different. In general, this principle works , but not always ... Some species may look nearly identical but in reality be incapable of reproduction with one another, meaning that ultimately those represent two, or more, distinct species. If genetic sequences (DNA) are now commonly used to identify such differences, other methods exist and in the case of 𝘊𝘩𝘳𝘺𝘴𝘰𝘱𝘦𝘳𝘭𝘢 all you have to do is to have the lacewings sing .
During courtship, lacewing adults will produce songs to attract potential mates of the same species. Those are known as vibrational courtship songs and there is no need to listen with your ears wide open, but rather to touch the substrate to feel the vibrations produced by the insect. By recording these “songs” and their exact frequency, it appears that different species will be using different songs, and the response of a particular species will be unique to the right song. This is how the species 𝘊𝘩𝘳𝘺𝘴𝘰𝘱𝘦𝘳𝘭𝘢 𝘱𝘭𝘰𝘳𝘢𝘣𝘶𝘯𝘥𝘢, once thought to be widespread in North America turned out to be in fact 3 species !
Green lacewings have some other tricks, as despite their names, they are not always green. Here two factors need to be considered. First, genetics may play an important role in determining body colouration. In rare cases, a lacewing may be a mutant due to genetic inheritance and having a yellow body color. Second, body colouration is a significant factor for individuals’ survival. In winter, they could turn yellowish, reddish, or brown temporarily during diapause (a state of seasonal dormancy adapted to adverse environmental conditions) and provide crypsis. By matching the color of vegetation seasonally, the risk of detection and consumption by predators could be greatly reduced. This kind of camouflaging property act as the primary defense mechanism of the 𝘊𝘩𝘳𝘺𝘴𝘰𝘱𝘦𝘳𝘭𝘢 genus, whereas other green lacewings genuses such as 𝘊𝘩𝘳𝘺𝘴𝘰𝘱𝘢 and 𝘊𝘶𝘯𝘤𝘵𝘰𝘤𝘩𝘳𝘺𝘴𝘢 defend themselves with a secretion with stinking smell from their endocrine glands (a group of cells or a “secreting organ” that excretes a chemical substance, for example, we have glands which secretes saliva), earning them the nickname of “stingflies”.
As we have seen lacewings are full of surprises and yet we only touched on the adult stages. The immature stages, the eggs and larvae, are also a great source for amazement that we will share in a future post. So stay tuned to the songs of nature played by the HKBM.
Text: Phoebe Leung
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