Ruud Kleinpaste: Bags of Silks

<p>One of the most incredible <strong><em>endemic</em></strong> insects in the collective New Zealand garden flies largely under the radar, yet it is as common as muck and lives for most of its life in a silk sleeping bag.</p> <p><em>Liothula omnivora</em> is known in the trade as the “bag moth” or “case moth”.</p> <p>Tiny, baby caterpillars spin themselves a small silken case in which they incorporate pieces of foliage, twigs, mosses or lichens, to either <em>jazz</em> it up a bit, or – if you are a boring entomologist – for <strong>camouflage</strong>.</p> <p>This Caterpillar silk is very strong indeed (try ripping a silk scarf in half!) and our case moth caterpillar's efforts are right up there in terms of strength. They carry their private bags with them as they move long grazing on foliage at night.</p> <p>As the insect grows, it extends it bag to suit its needs. Along the way it feeds on its favourite host plant (often conifers, but also titoki, roses and even elms or flax) and adds more desiccated plant materials to its bag, to blend in with its surroundings.</p> <p></p> <p>In the New World car park at Kohimaramara I once found a whole colony of case moth bags constructed of bits of torn plastic shopping bags; these bags were blown about and trapped by the fancy <em>Chamaecyparis</em> bushes on which the larvae fed.</p> <p>I even heard of liberal European entomologists, no doubt indulging in mind-altering substances, providing their captive colony of case moths with psychedelic bits of coloured paper – just for a laugh.</p> <p><strong>Technological Tricks:</strong> At the top of the bag the caterpillar has constructed a draw-string system: when there’s trouble brewing, the insect can withdraw into its case and quickly close the opening behind it.</p> <p>One simple movement. Safety!</p> <p>A similar draw-string contraption exist right at the bottom of the case. It avoids the problem of ablutions in the bottom of the sleeping bag.</p> <p>Makes sense too!</p> <p>The pupa, or chrysalis is also form