Butterflies and Ants feeding on plant sap along the same branch

“In a small patch of forest which remained between the Bt Panjang Park and a fast developing condominium complex alongside Petir Road, a pair of Bigg’s Brownie butterflies (Miletus bigsii bigsii of subfamily Miletinae) were seen feeding on some kind of plant sap of a young Syzygium plant. Despite the noisy environment of the nearby construction works and the photographic attention they were getting from our group of butterfly watchers, the Bigg’s Brownies remained totally absorbed in drawing up the plant sap they had found.

“Another interesting observation was that there were also many small, dark reddish looking ants which seemed to be doing exactly the same thing as the butterflies, namely sucking the plant sap. We do not know who arrived on the branch first. However, we could not discern any animosity between the feeding ants and butterflies. The scene appeared to be calm and amicable – no pushing nor biting between the different feeders. The butterflies were seen probing actively with their proboscis for the sap, and their activity was uninterrupted. In fact, we saw a few ants climbing quickly on and over the wings of the butterflies. This action looked to us like an attempt to move on to another part of the branch, and was not an aggressive stance.

“Literature on the taking of plant sap by butterflies explained that it is a way for them to gain essential nutrients besides the more usual and known way which is drinking nectar from flowers. It was also highlighted that for some butterflies, they would only drink the sap from one specific species of plant.

“We did a quick lookout for more Bigg’s Brownie in the area to ascertain if they would be feeding on the same kind of Syzygium plant. A few more Bigg’s Brownie butterflies were observed in another narrow strip of the forest further into the Bt Panjang Park. The same behaviour was observed. The Bigg’s Brownie was feeding alongside the small, dark reddish looking ants, only the plant they were on was different! This was a creeper commonly known as Mile-a-Minute (Mikania micrantha).

“At another location – Upper Seletar Reservoir forest – we also observed another kind of butterfly – the Pale Mottle (Logania marmorata damis) feeding alongside the same kind of ants, but on another type of plant – Common Tree-vine Leea indica) (above).

“Videos show the Bigg’s Brownie butterflies and ants feeding on 2 different kinds of plants – Syzygium and Mikania mscrantha, while the photo shows a Pale Mottle butterfly feeding with the ants on a Leea Indica sapling.”

Amy & KC Tsang
Singapore
July 2013

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