Did you know that grasshoppers can fly? You probably do. My first encounter with this large, black and yellow species proved that they only can fly, until there is a window in their way. They make quite a loud knock when they hit the glass. I was impressed that this specimen managed to sit on the glass after that impact. In fact V. nigricornis is one of the few large insects that can be found in residential areas. They are huge, but compared to Aularches miliaris, they are slimmer. Usually the commonly found insects are the ones you don’t look at, but this nice species has some interesting stories!
In Singapore, as well in as many other countries, there is a regular anti- mosquito fogging. I assume that this fog eliminates not only the mozzies, if at all. While you would find other crickets, spiders and bugs in non-fogged areas, the fogged placed would only hold ants, a few jumping spiders, and flying insects. I guess the ability to fly is why we can find the “Glass hopper” there.
The fog will be spread weekly and generously in Singapore. It is impossible to avoid inhalation, because it will just suddenly start, and the fog comes in large clouds, leaving a light chemically tasting air for a few minutes. So how can a toxin be selective for mozzies? Let’s see.
The effectiveness of fogging seems to be under discussion, and at least questionable. I can myself confirm that adult mozzies behave like I do, they fly away (ok I rather walk). In fact we have more mozzies in our house on fogging days. Since the “mozzie wipeout” has to be done by everyone (means avoid to create breeding opportunities), it is not an easy task. Posters and controls are used to create awareness in the communities. And I would say there are usually not too many mosquitos in Singapore. This has also to do with Project Wolbachia, which was recently released (end of 2021) in Singapore. See here more info about Wolbachia!
But what is the chemical they fog around? First of all, the intention is to prevent diseases carried by mosquitos, that’s important. The WHO has formulated a statement here. Not easy to find out! But I found a list of registered repellents and pesticides. That’s already 31 pages long. When you search for Mosquito in that document, you’ll find substances like Transfluthrin, d-allethrin or Cyfluthrin. They are all related, and the core structure is called Pyrethrin. Those substances can be found in the Dalmatian chrysanthemum, Tanacetum cinerariifolium, which belonged to the genus Pyrethrum previously, hence the name. So the active ingredient is most likely this plant based substance. Yes and no. I would rather say it is inspired by a plant, but what we are using is synthetic, and chemically modified substances inspired by plants. That’s why we have so many different names for pyrethins. They are nonspecific insecticides, and here’s the key. Bees, beetles, any kind of insect is fogged away. UV light degrades the pesticide, but without UV light it is stable for years. So mozzie-fog accumulates e.g. in houses and can be detected in the dust.
One more thing, before we talk about the locust again. To make the pyrethins know out mozzies faster, a synergist is added to the liquid. This is piperonyl butoxide, or 5-{[2-(2-Butoxyethoxy)ethoxy]methyl}-6-propyl-2H-1,3-benzodioxole. This molecule has a similar story as the pyrethins, it is a modified version of a plant based material (called safrole). This material hinders the natural toxin-breakdown abilities of insects, so that the pyrethin can act stronger. PBO is also related to Piperonal, a fragrance and flavor. There are of course numerous studies on the health effects on humans, and there are regulations of how much of what can be used. Still I hold my breath and walk away from fogging. And still I see more insects in areas that aren’t fogged.
Their appearance of V. nigricornis is something: bright yellow and black make a nice contrast. The younger ones are rather green, with some black, but to be honest I’m not sure how to identify them. There is at least one similar, but much smaller locust around, and some other species that could have similar looking babies as well. You usually see them sitting somewhere eating. If left alone, they can sit and eat in the same spot for days. When you get too close, they jump off and fly away. As with other locusts, they often go your way, and I’m not sure if that is totally accidental.
A German zoologist, Hermann Burmeister, described this species from Singapore in 1838, so we can say V. nigricornis is a real local Singaporean! There are several subspecies all over Asia. See the original document from 1838 here! Look at page 629, he described it as Acridium nigricorne, with an asterisk. I couldn’t find any information related to that. So there isn’t much description about this species, except for the color and size (1 2/3″, what is 42.4mm). Sir Boris Petrovitch Uvarov establisehd the genus Valanga in 1923 and our species was transferred. On page 143 is Valanga mentioned, and again it has an asterisk, but this time followed by something. It comes from the Javanese word for locust, valang! Today this species is in the familiy Acrididae with over 7,600 species, and the subfamily Cyrtacanthacridinae.
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