Exploring Pigeon Valley: The Red-line Sapphire butterfly

This is the 105th article in an ongoing series that highlights the riches of Pigeon Valley, the urban nature reserve in the heart of Glenwood. The focus of this article is on the Red-line Sapphire butterfly.

The photo shows one of our beautiful Sapphire butterflies; however, the context is very sad. The Red-line has as its host mistletoes, the plants that are parasitic on trees, and here it is on the leaf of the Banded Matchflower mistletoe (I hear you say, Of course! It’s Oncocalyx quinquenervius!). The sadness is because the host tree for the mistletoe is a majestic Natal Elm (Celtis mildbraedii) just outside the fence on King George V Avenue, and, in the recent rains, the one trunk of the tree collapsed, bringing down a great mass of mistletoe.

We don’t know if the death of this section was caused by the attack of Polyphagous Shothole Borer, the invasive alien borer, that had already caused damage to the tree, or possibly the immense growth of this mistletoe had become too much. The Elm is very rare, the mistletoe, which is also hard to find, is host also to the rare Short-barred Sapphire; Steve Woodhall, the butterfly expert, actually once watched a Short-barred emerge on this same tree. Fortunately, there are other patches of this mistletoe in the reserve, one which I found immediately after seeing the damage to the Elm.

ALSO READ: Exploring Pigeon Valley: Hover Flies

One, very indirect, positive from this. On Friday I went to view what had happened. At which point some municipal employees up on the bank asked me where the sewage blockage was that has for weeks caused sewage to flow through the reserve. So we headed up along the fence and they got their jetting machine in place to fix the blockage. I hung around to ensure it was done. It turns out that the blockage was caused by some residents connecting stormwater drains to the sewerage system, which brings in sand and stones, as the workers showed me.

We get frustrated with the municipality, but in the end, they did not cause the problem – local people did – and finally the municipal workers fixed it. So the stream has ended; unfortunately, though, there is now a further blockage down the line that I have reported.

Crispin Hemson chairs the Friends of Pigeon Valley, a group that undertakes clearing of alien plants, keeps records of bird and mammal sightings and alerts management to any problems.

The Friends have a monthly walk at 7.30am on the second Saturday of each month. Email: friendsofpigeonvalley1@gmail.com.

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