During my ten-day visit to Dalhousie in the end of May and early June this year, the weather on most days was cloudy, with a hint of sunshine. This meant that the butterfly activity during our long walks was subdued, and hence I had to fall back on my secondary interest — that of watching moths.
On many nights, I set up a white bed sheet (borrowed from the caretakers of our home) with a 160 W mercury vapour bulb, which serves to attract more moths than a CFL or the incandescent bulb that we normally use in our homes. On rainy nights, I mounted the bulb and the sheet in a shed so that the moth screen was sheltered. The reason I needed to do this was that the mercury vapour bulb gets really hot, and even a few raindrops will cause the bulb to burst. On clear nights, I could set up my moth apparatus outside.
Our house is mostly surrounded with conifer and oak forests and is at a height of 2,300 metres. There are only a few houses near ours, which is great, because this meant that the light pollution was limited, a crucial need to attract moths. The other factor that was in my favour was that the new moon night was on June 27, and the complete darkness helps attract more moths onto the screen.
My moth sessions during the ten-day visit were terrific. I recorded at least 300 moth species, though I am yet to identify all of them. Among my favourites was a tiger moth (Areas Imperialis). This stunning moth visited the moth screen on many nights. I fell in love with its pattern and colours. The moth screen also attracted another creature — the bat. Some nights, I could see the bats whizzing around the screen, attracted to the moths on offer. Do you know how bats hunt for food? They do so by echolocation, i.e., they produce ultrasonic sound waves and use their large ears to pin point the location of their prey. The tiger moth has a few tricks up its sleeve to counter the bats. It produces its own ultrasonic sounds to confuse the bats! Aren’t these creatures amazing?
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