Spiders, beetles, millipedes, for sure. Moths? Maybe. Butterflies, like the lemon pansy (Junonia lemonias) in the photo above? A stretch. Crabs and lobsters. Certainly not; that’s food! Have we reached the limits of the folk classification of visible bugs? Consider. Spiders are perhaps more closely related to horseshoe crabs than to beetles. And if you think sea lice are bugs, then their close relatives, the shrimps shouldn’t be exempted. So let me go with arthropods instead: those invertebrates with an exoskeleton and jointed legs and segmented bodies. (Ands are powerful things, easily lifting fifty times their weight in sentences. After all we have jointed limbs, and segmented vertebrae. But we are not arthropods, because we are not invertebrates.) I’ll go with this, because it gives me a reason to finally read two papers (this and this) that I’d been meaning to for a while.

When did arthropods come into being? Darwin noted an uncertainty: “For instance, I cannot doubt that all the Silurian trilobites have descended from some one crustacean, which must have lived long before the Silurian age, and which probably differed greatly from any known animal.” Darwin’s intuition has been vindicated by the discovery of new fossils which pushed the origins of arthropods beyond the Silurian period (445-420 million years ago) into the Cambrian (535-490 million years ago). I took this photo of a fossil arthropod, a trilobite, in Shanghai’s Museum of Natural History. That bug was the size of my hand! The species, Sinoptychoparia tuberculata, is known from this single specimen from 515 million years ago, preserved in a sheet of stone from China’s Guizhao province. The oldest fossils of arthropods that we know of are not more than about 550 million years old, embedded in the proliferation of animal forms that is called the Cambrian explosion. This roughly agrees with genetic information.

Of all the forms of living beings known and recorded, arthropods are the most varied. But the living species of arthropods are just a small fraction of all their extinct cousins. All of today’s arthropods are either crustaceans, insects, myriapods (millipedes, centipedes and their relatives), or chelicerates (spiders, hermit crabs, and related species). But there are many groups of animals which seem to be closely related: tardigrades (which recently failed to colonize the moon) and velvet worms certainly, but also roundworms. In Darwin’s time it was expected that arthropods must have evolved from the much older group of roundworms, the annelids. The biggest discovery since Darwin’s days is that genome analysis shows that arthropods do not come from annelids. I think that is my biggest take-away from the first paper. These genomic studies have completely rearranged the branches of the tree of life around arthropods into a form that Darwin would not have suspected.

Insects evolved from cave-dwelling crustaceans about 480 million years ago, late in the Cambrian period (that’s the headline of the second paper). Beetles began to develop about a 130 million years later. They have had time to evolve into a variety of shapes. So many, in fact, that J.B.S. Haldane remarked that “If one could conclude as to the nature of the Creator from a study of creation it would appear that God has an inordinate fondness for stars and beetles.” All insects have a pair of antennae to smell with, but the one I saw on the beetle on the wall outside my flat was really spectacular. This photo was taken in October 2019, and I saw another specimen in November 2022. So, whatever it is (help me if you can, as the Beatles implored), it is not uncommon. There are many ideas, but no certainty yet, about how antennae developed.

If you wander through the fossil section of a museum, you are likely to see insect fossils similar to today’s lacewings and dragonflies. All have two pairs of wings like modern insects. The earliest known fossils of winged insects are a little more than 300 million years old, but genomic studies now show that insect flight arose about 400 million years ago. So, one should expect fossil hunters to discover even older specimens. I’ve written earlier about how a butterfly is grounded by a predator taking a bite from its forewings, but it can continue to fly with reduced manoeuvrability even after losing large parts of its hindwings. Flies seem to have only one pair of wings, because the hindwings are reduced to small appendages called halteres. They lose control over their flight paths if the halteres are lost. Beetles have converted one pair of wings into a hard cover, and still retain an ability to fly. I wonder whether dragonflies and damselflies can also keep aloft without using their hindwings.

Ants are fascinating. With the wonderful cameras that many of us carry in our pockets, I’ve been looking at ants in detail for some years now, without being able to identify them. These have elegant striped bodies which were quite hard to see at first because of the lack of contrast with the flower they are clambering over. When we think of pollinators, ants are not the first to pop into our heads. We think first of bees and butterflies. Interestingly, both these families have their origins before the rise of the flowering plants. Their spectacular diversity, however, comes with the explosion of flowers about a 140 million years ago. Ants also date from that time.

The origins of spiders and related groups of animals still remains to be understood fully. Early ancestors of today’s spiders are visible in the fossil record in the middle Cambrian. Animals that we would perhaps recognize as spiders may have lived about 400 million years ago. They have had time to evolve into the many lifestyles we recognize today: the orb weavers, the jumpers, or the ambush hunting crab spiders, like the one in the photo above. Arthropods are an old order of animals, filling a variety of niches across the world. Even insects are much older than flowering plants. So tales of the insect apocalypse are overblown. If we heat our world beyond our limits, we might carry some arthropods into extinction with us (lobster claws could become rare), but far from all.

Against the light

The warm mid-morning sunlight and the cool air of the garden made me lazy. There were butterflies fluttering around the edges of the lawn, but I did not want to get up to photograph them. “I have a monster zoom,” I told myself, “let me use it.” Easier said than done. These marvelously bright and colourful creatures can disappear into the background when they want to. I saw a common pierrot (Castalius rosimon) flying around a tree, but every time it sat down I would lose sight of it. Eventually I managed to figure out where it was going back to sit each time, and focused on those leaves. After I got the photos (one is featured) I realized that it was disappearing into the bright light reflected from the surface of the leaf. The bright patterns on its wing broke up its outline very effectively, exactly like the camouflaging stripes on a tiger’s skin. You cannot imagine a tiger being unspottable when you see it in photos, but when you are trying to spot one in the dappled sunlight of the jungle it is very hard to see. The common pierrot is similar.

I’ve usually been extremely lucky with the lemon pansy (Junonia lemonias). I’ve often caught this butterfly with its beautiful black and white spots on tan forewings, the four eye spots bright, sitting with its wings stretched out on a sunny leaf. This time it was fluttering around a hedge, coming down in the open and suddenly vanishing. I followed it with my eyes for a while, and then looked through the camera. The camouflage was incredible. It would disappear on the open lawn. As it came to rest on blades of grass, the pattern would fool the eye into seeing it as little bits and pieces of brown earth. The eye spots serve a different purpose: distraction. When a predator, such as a bird pounces on it, it can be fooled into thinking that these spots are eyes, and bite at that part of the wing. You may have seen butterflies without part of their wings. That’s often due to birds misjudging where to strike. Losing a portion of the hind-wing does slow down a butterfly, but it can still manage a slightly slower flight. Laziness taught me something that morning!

Four butterflies and a moth

A decade back Mumbai was full of butterflies. You could see the bright grass-yellows fluttering in and out of traffic wherever there was an island with some greenery. If you stopped near one at a traffic light, you could see the fluttery flight of a Psyche or the almost invisible motion of small grass-blues. The potted plants in our balcony would be visited regularly by a host of larger butterflies, and on a Saturday afternoon I would take my camera and go for a half hour walk in the garden to take photos of a variety of these delightful animals. Then with the rise of mosquito-borne diseases, everyone decided to pump huge amounts of insecticides into our cities, and the butterflies suddenly vanished. The fluency which I had picked up in identifying butterflies also faded away.

Now, when I see butterflies during a walk in a forest, I feel like I can barely remember a few words of a language which I once knew well. The lemon pansy (Junonia lemonias)in the featured photo brought back a quick memory. I realized that when you have forgotten names, you see fewer butterflies. During our trip to the jungles around Thattekad I tried to train my eyes again to spot Lepidoptera, and I did manage to catch a glimpse of many Nymphalids (brush foots), Lycaenids (blues), Pierids (yellows), and Papilionids (swallowtails), from the little grass-blues to a fleeting glimpse of the yellow-and-black Southern Birdwing, India’s largest butterfly.

Butterflies are an undemanding pastime. You don’t have to wake up at unearthly hours to see them. They become active in the middle of the morning. The six-lineblue (Nacaduba kurava)that you see in the photo above is a typical low-level butterfly. The upper surface of its wing is a shimmery greyish blue. It hovers usually in bushes and undergrowth at the level of your knees, but comes to frequent stops to perch on a sunny leaf. If it settles on a chest-high leaf, grab the chance to take a photo. It will usually wait for you to take several shots.

The common bluebottle (Graphium sarpedon), like most larger butterflies, inhabits a higher world in the forest, often flying at a level above my head. It is harder to photograph, since it perches for a very short time. I managed to take the photo that you can see above because around noon it decided that it had had enough sugars, and needed some of the minerals that it can only suck up from wet mud. Such mud-puddling butterflies give you a great opportunity to take photos.

The butterfly which you see above is the Psyche (Leptosia nina). It is so common and widespread that think of it as the sparrow of the butterfly world. You can see its weak and fluttery flight everywhere there is some grass or some low bushes or herbs. I noticed this butterfly as far afield as in the Andamans and Myanmar, and it spreads well beyond that to the east. Like the lineblue, this is another small butterfly which flutters among vegetation below your waist.

There are very few experts on moths. These are vast families of Lepidoptera which defeat an amateur. The relatively smaller number of butterflies are easier for amateurs to recognize because they are well-differentiated by wing colours and patterns. Moths are often drab, well-hidden, and requires finicky attention to differentiate from each other. I took this photo of a day-flying moth perched on a leaf. You can tell that it is a moth and not a butterfly by its antennae. All butterflies have the thin antennae with a club-head at the end which you can see in the other photos. Moths have a wide variety of antennae: the extremely feathery antenna of this one probably means that it is male. Some day I must make a trip with an expert on moths.

Butterflies before breakfast

I was trying to trace a persistent error message in my camera and eventually found that it was due to a lost set of photos taken two years ago. I’d taken them during an early morning walk to look for birds inside Nameri national park, on the border between Assam and Arunachal Pradesh. On the way back we saw a large number of butterflies in a space of about 15 minutes. I managed to photograph a few of them. This is what biodiversity means!

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