Down in the jungleland: Agent Orange

Wasps do us a great service by controlling the population of caterpillars and aphids.

Written by Ranjit Lal | Published:January 3, 2016 1:00 am
The great banyan tree and around 1,000 of its relatives are pollinated by the tiny fig wasp. Each species of the tree has its own species of wasp to pollinate it. No other can do the job. The great banyan tree and around 1,000 of its relatives are pollinated by the tiny fig wasp. Each species of the tree has its own species of wasp to pollinate it. No other can do the job.

At the outset let me insist I have nothing personal against wasps, or that I’m writing this only now, in the dead of winter because that’s when most of them are kaput and won’t see this and get their sentiments all gingered up and start priming their stings. Suffice to say, different insects evoke different reactions from one: ants, no matter how ferocious their reputation, always look a bit goofy and make you grin, cockroaches disgust you, bees remind you of flying furry teddy-bears, dragonflies of WWI fighter planes. And wasps? Alas, there’s something alien about them: that cold, metallic demeanour, those blank, shuttered eyes (so exploited by horror sci-fi filmmakers) the icy ruthlessness about their movements. And again, I must insist this has nothing to do with the fact that a jaundiced yellow wasp once sunbathed on my neck in the swimming pool, eyeballing me coldly, before biting me because I hadn’t any ice cream to offer.

They’re a pretty successful family of insects, over 1,00,000 species strong and counting, and along with ants and bees have descended from a common ancestor. The largest, the Asian giant hornet (also found in our neck of the woods) may be 2 inches long, the smallest, just 0.008 in. long. Social wasps, usually those yellow or orange guys, or the dangerously striped hornets, live communally, fashioning their homes out of plant material, wood fibre, mud, and saliva depending on their species’s preference. They are ruled by a queen (some not quite dominantly as queen bees rule their hives) and may be omnivorous, eating rotting fruit, vegetables, nectar and carrion, which is why they swarm around fruit and sugarcane juice vendors in marketplaces. They guard their homes ferociously and do not tolerate visitors. A small colony was once established in a weep-hole outside the dining room: the actual nest was down a small shaft in the hole. At least one wasp (see photo) would stand guard outside this — and she could sense movement from at least 10 feet away, swaying gently in the direction I moved my hand or finger. If I came closer, she would unfurl her wings to make herself look larger and more threatening. And all the while, those implacable cold eyes would be pinned on me.

Most wasps, however, are solitary and they’ve sort of specialised in becoming ferocious, single moms. They mate, find a lair to lay their eggs, provision it for their young, seal the nest and are off to begin the whole process again. That provisioning part is where matters become a bit macabre. One monsoon, many years ago, I watched this metallic green slim-waisted wasp wing into my room and disappear inside a screw-hole in a bookshelf. A few minutes later, she emerged, flicked her wings impatiently and was off. She did this repeatedly. Closer examination revealed that every time she returned, she had a small spider in her jaws, which before entering her lair she would sting by curving her rear end into it. Eventually, she began sealing the entrance with what appeared her own brand of Plaster of Paris. In the interest of science, I broke open the lair and emptied it out. Nine or 10 tiny dead spiders fell out. But then my skin crawled because the “dead” little spiders crawled too; they moved their limbs around in slow motion as if groping for help. And on one of them, a horrible translucent yellow grub had snuggled down and made itself more comfortable as it sucked the spider dry. The wasp mom had merely anesthetized her victims to ensure her young one would have fresh (as against rotting) meat to feast on when it hatched.

These wasp moms actually do us a great service — in this gruesome manner albeit — by controlling the population of insect pests such as caterpillars and aphids. Wasps are not too much into the pollination business — the way bees are — but some of those that have specialised in this are at the top of their game. The great banyan tree and around 1,000 of its ficus relatives are pollinated by one of the tiniest wasps around —the fig wasp.

And get this: each species of fig tree has its special custom-made species of fig wasp to pollinate it. No other can do the job. The head of each species of wasp is shaped like a special key that fits exactly into the tiny “keyhole” at the top of the fig it is destined to be with. The fig or drupe, actually hosts hundreds of little flowers inside it, male usually crowding near the keyhole, female flowers deeper within. The tiny female wasp enters the drupe, lays her eggs in about half of the flowers inside and dies. The eggs hatch, the larvae feed on the developing seeds in the flowers and turn into tiny wasps. Most are females; the few (wingless) males that hatch, mate with these — still inside their flowers — and die. The young females eat their way out, daubing themselves with pollen from the male flowers near the top and fly off, seeking another fig tree in which to lay their eggs. As they enter the drupes of these, they pollinate the female flowers. Suffice to say, the giant banyan (the tree of life) is dependent on the tiny fig wasp for propagation. As also, the tiny wasp is dependent on this giant tree for the same reason.

Thus are giant egos cut down to size, and tiny egos inflated beyond measure!

Ranjit Lal is an author, environmentalist and birdwatcher.