Moths are back!

After two years I’m beginning to see the moth population in our garden slowly recovering from the frequent chemical baths that became part of the hygiene theater of the pandemic. One of my favourites is the one in diaphanous tutu with a gold border that you see in the featured photo. It was a little more than two centimeters across in size. Most moths do not have common names, so I know this only by its binomial Cydalima laticostalis. It is a member of the grass moth family, Crambidae. I should start calling it the gold-and-satin moth. Maybe it will catch on.

I find it useful to think of moths first by size. The two that you see above are between one and two centimeters across. One of the reasons moths do not have common names is that it is very hard, impossible, to pinpoint species by sight alone. The spotted yellow moth is clearly a member of the genus Conogethes, but this is a massively speciose genus. An attempt at DNA barcoding found that there are many species which were not recognized as different until the genomes were studied. By appearance this moth seems to be a member of the Conogethes punctiferalis complex, one of the many agricultural pests. The other, ivory and chocolate banded moth, is a member of the genus Nosophora. Both these are grass moths, in the family Crambidae.

This moth is smaller, about half to one centimeter across. It is enough of a pest that it has a name: a teak leaf skeletonizer. It is a member of the Paliga damastesalis species complex, containing also the P. rubicundalis and the P. machoeralis. It is impossible to tell these three grass moths apart by sight. I had no desire to extract its DNA in order to identify it better.

Previously I’ve completely ignored moths which were less than half a centimeter across, like these two. But now with my macro lens I can see that they are both likely to be grass moths, ie, in the family Crambidae. That brilliant wine red colour should make this quite recognizable, but all the web sites I consult for identification also seem to ignore these smaller moths. Let me see whether I can nudge them to start working on these smaller ones. Whether I can identify them or not, I’m glad to see that the local population of moths is slowly recovering from the COVID-induced hygiene theatre of spraying everything around us with strong pesticides. Perhaps the bee-eaters and fly-catchers will also be back in a year or two.

The arriviste

When I saw three of these spectacular moths together, they were the first I’d sighted in two years. The satiny look of their wings, with the gold forward edge makes the Cydalima laticostalis a favourite of mine. One of the sad things about our pandemic lockdown was the complete disappearance of moths. Did the virus destroy them? Insects often have analogues of the ACE-2 enzymes that the virus attacks in humans, but are distant cousins of the variant that circulates in our bodies. We know that the SARS-CoV-2 virus cannot breed inside mosquitos. So it is unlikely to have been directly affected. Instead, the extreme amount of pesticide sprays used in the health theater of the first six months of the pandemic must have put and end to them. I was happy to see them coming back.

In the next few days I saw more moths: a legume pod-borer (Maruca vitrata), one or two rice leaf-rollers (Cnaphalocrocis medinalis), and the stranger above, which I first mistook for an old friend. I began to find something odd about the whole thing. What I was seeing were moths which were uncommon or unknown in my neighbourhood before the pandemic. What happened to what were once the common ones: the beet webworm moth (Spoladea recurvalis), the banded pearl (Sameodes cancellalis) or the yellow-tailed tussock moth (Somena scintillans)? Perhaps the excessive spraying of pesticides killed them off, and now the city is being slowly repopulated by moths which have just flown in from the countryside around us into what they must see as a new world. I have to make friends with my new neighbours, so can anyone help with ID for the one in the photo here?

A gold and satin moth

It is hard to believe the diversity of moths visible in a city like Mumbai. In recent months I’ve taken to scanning external walls of my flat, near lights which stay on all night, and usually I’m rewarded with the sight of a few moths which seem to like to stay in the open all day. Recently I came across an auld acquaintance, the spectacular Cydalima laticostalis. Before you begin to wonder whether you should dedicate your life to recording moths, I should warn you that it is hard. Unlike birds and butterflies, no one has bothered to give them wonderful common names, so you will often have to remember the Latin binomial. Also, there are too many varieties to capture in field guides, and the colours are extremely variable, so you might see a green moth which turns out to be the same species as the brown moth you saw three days ago. Conversely, there are myriads of species complexes, which are groups of species which are so closely related that they cannot be told apart by eye.

The featured photo was taken this moth on an east facing wall in the morning sun, and my smart phone’s AI assistant was left a little confused about colour correction. The true colours of this moth are more easily appreciated in a photo I took on one October morning in 2006 in a well-lit but shadowed area in my flat. I was struck by the satiny appearance with the gold marginal border. It took me a couple of years to get a good ID (yes, there are very few moth experts) and to find that it is a leaf skeletonizer, a moth which lives by munching the green crunchy bits off leaves, leaving a beautiful but useless skeleton. Reports are so sporadic that I think this blog may be the first report of it being spotted in Maharashtra in Febraury. I have no idea when it breeds, or what it looks like as a caterpillar. After the box tree moth, Cydalima perspectalis, became an major invasive pest in Europe, the first modern genetic-taxonomic study revealed that its closest cousin was this leaf skeletonizer. Progress is slow.