During summer, the water level in the Bhadra reservoir goes down, exposing a strip of land. Several plants use this opportunity and grow for a few months until the land is submerged again as water fills up in the reservoir during the monsoon. Among the several plant species that spring up, the Heliotropium shrubs are of particular interest to several Danaid butterflies.
I was staying at the River Tern Lodge, Bhadra – in my opinion the most beautiful of the Jungle Lodges & Resorts camps. Early in the morning, I went on a boat into the backwaters to soak in the beautiful landscape, hoping to see some wildlife. As the day got warmer, I decided to return to the camp. I had just reached the jetty when I was enthralled by the presence of a sizeable number of Danaid butterflies congregating on the Heliotropium inflorescences.
Having feasted my eyes on the butterflies, I decided to walk up towards the stairs that lead to the cottages. At this point, I heard a cicada calling from very close by. I looked around and found the cicada on the ground. This came as a surprise because cicadas are generally seen on tree trunks where they are well camouflaged. It is from here that they conduct their orchestra.
On closer observation, I saw the cicada in the grip of a robberfly! The robberfly was much smaller than the cicada itself. The cicada was still alive and making the characteristic sound – but only this time it was the cicada’s swan song. A few minutes later, this sound died down.
This incident took me by surprise! I was in the open and there was no tree or any tall vegetation in the immediate vicinity, say about 20 feet around me. Perhaps the robberfly caught the cicada in mid-flight as they are sometimes known to do! I will never know. It would have been wonderful if I had witnessed the whole act as it transpired.
Robberflies are robust insects that are known for their ability to hunt other insects. I have seen them making a meal of insects of various sizes – some prey on creatures even twice their size! Robberflies have a pair of large compound eyes. They also have a strong dagger-like proboscis hidden within a ‘beard’. All these enable the robberfly to deal with the prey effectively. The stiff proboscis is pierced into the prey as it is caught. In the process, the saliva of the robberfly is injected which not only immobilises the prey but also digests the innards of the prey. The prey is then sucked dry.
Robberflies are a large group consisting of over 7000 species worldwide. Being such a diverse group, they occupy different niches. And, being predatory insects, they help in maintaining a control over the population of insects that they feed on.
The next time you walk through shrubbery or for that matter any patch of wild growth, keep your eyes peeled for there is every chance that you may just be standing next to a robberfly.