A parasitoid in lapis lazuli (2016.02.01 [Mon.])


  As I was doing some housecleaning, I spotted an interesting insect on the window. Not the typical bush cricket, at first I thought it might be a fly, but no it was more like a bee. Closer inspection revealed it to be a cuckoo wasp (Praestochrysis lusca). I caught it and had it ready for mounting that day. This wasp is a parasite of the blue mud dauber, Chalybion japonicum. Mud dauber wasps carry spiders into their nests where they lay eggs and allow them to feast on their prey. So for the cuckoo wasp, rather than seeking out and invading a mud dauber’s nest it would seem to be easier and more nutritious for one’s young just to collect some spiders directly. But clearly the active parasitic life hold great attraction for these insects, who then are we to judge?

  I went on a cuckoo wasp hunting expedition three years ago in a secret spot behind a certain train station. All the passers by made it impossible to capture anything, but I remember one vivid flash of ultramarine that could only be my chrysidid quarry. I saw many blue mud dauber wasps in that location, so encountering a cuckoo wasp came as no surprise. The daubers themselves are beautiful creatures, as blue as their name implies. Their abundance here, as opposed to the typical red-banded sand wasp (Ammophila sabulosa) makes this a special place. Normally I would be disgusted with any bug with the temerity to parasitize the lovely mud daubers, but since cuckoo wasps are without question the loveliest wasps of all, I can only resign myself to them feeding away. Like using a prawn to catch a red snapper, or something like that? (Or not?)

  The cuckoo wasp is beautiful enough, but its larger cousin, Stilbum cyanurum, the largest chrysid in Japan can also be found here, although in this case the concept of ‘large’ is relative as it only grows to about 20 mm. Why so small? Well, their preferred host is Oreumenes decoratus, a solitary eumenine wasp. As a grade schooler, I chose these wasps for my summer study project (although I never managed to find one). They’re something like a boss version of the potter wasp, Eumenes rubronotatus, which builds a cute little pitcher while O. decoratus wasps only manage to craft a hovel of mud.

  The majestic large cuckoo wasp is often mistaken by casual observers for a large greenbottle fly. But they exert a deeply relaxing effect on me. I have one mounted under my microscope, and after enduring yet another long, meaningless meeting, or whatever other perverse fate befalls me, I take a moment to gaze at its beauty. Yes, it’s a healing bug.

  What is the function of that metallic sheen? Whenever I ponder this, I can’t help but think of the exquisite jewel beetle (Chrysochroa fulgidissima) and Delacroix’s painting ‘The Barque of Dante.’ This jewel beetle’s wing features a vivid green base overlaid with a pair of red stripes bordered in yellow—the primary colors (see image). But when nestled in summer foliage, it blends perfectly into its surroundings. Following a similar principle, Delacroix used red, green, and yellow to create sparkling sea spray (I haven’t yet been able to visit this masterpiece, but apparently he used no white paint in making this effect). It seems that both of these great artists used prismatic effects to evoke an iridescent dimensionality.

  Many insects use chiaroscuro to create a sense of solidity, but glossiness can be used to the same purpose. You may not believe it but when the lobster moth species, Tarsolepis japonica japonica, is resting on a wall, it silver wing spots could be mistaken for stag beetles.

  Shamelessly, I bought another specimen at the insectarium, a lustrous swallowtail, Papilio peranthus fulgens, dressed in a luxury that recalls the bewitching Black Lizard celebrated in Edogawa Rampo’s mystery novel of the same name. It sits glittering sinisterly in a corner of my room.

  The same evening that I discovered my P. lusca, I was paid a visit by the utterly somber macromoth Hypopyra vespertilio. An auspicious midsummer’s eve for meeting lovely insects...