Diary: Saturday 23rd March 2002

Conditions at New Brighton

SUNRISE: – 6:34 am.

TIDE: – Low 5:13 am. (0.6m)

MOON: – Set at midnight, rise 3:18 pm. A day after first quarter.

‘At 6:30 found about 8 tracks of small scarab larvae (?) only.(Wasn’t too sure as some tracks were smaller and different) All large tracks gone. Then success, found a live one ready to dig in, (it was motionless in the thin film of water) but was a larva of another sort, a little over 30 mm long! Just a little caterpillar, how can that be?

Sandcut Worm preparing to dig in

A Sandcut Worm attempting SSL’s trick

Put in a film can. Followed another one of the caterpillar tracks and then at 6:45 found a fine set of SS Larva prints. Dug a hole at the ‘exit’ (recent looking diggings in the sand I presumed to be the exit) to check it wasn’t an ‘entry’ hole, but nothing down there. At the other seaward end of it’s trail found many gull footprints, so that was the exit and that’s that. (6:45) The Larva was heading towards the sea when it was nabbed.’

Sand dunes. Sketch from diary of Sand Scarab Larva Route

The small caterpillar had traveled out there possibly the night before last, dug in, and last night felt the need to shift to ‘deeper waters.’ The two caterpillars had traveled what looked like all the way from the dunes, although the marks in the sand could only be seen going about halfway up the beach, heading for the dunes, a distance of 80 yards maybe. That’s a long way for such a tiny caterpillar.    

Then another (caterpillar) was found just past the South New Brighton Surf Life-saving Club and it seemed rather disoriented as tracks were all over the show once it reached the wet sand of the low tide zone. Brought both home and some wet sand, filled a glass buried it flush with the sandpit surface. Put both caterpillars (CP’s) in there a finger width down and covered. Poured salt water on top til it lay on surface. Two hours later one had come back up and wandered off and burrowed into the sandpit.’

NB. Although these caterpillars were found accomplishing what evidently appeared to be the same ‘tricks’ as SS Larva, I must state that I did not hang around to observe them actually digging into the wet sand to disappear below the surface, although as you can see from the photo, it looks as if that is about to happen. Perhaps they do not, and I whisked them away to the sand pit too soon, but why else would these insects bother crawling down to the sea’s edge, all that distance away from the sand dunes which are their home, if they were not achieving a similar end.

I guess I missed my chance to observe them properly and now with Winter upon us here in Christchurch it may be that their marine activities will not be seen until next Spring, Summer, or, (as I prefer to assume,) Autumn.