This young first instar caterpillar had only been feeding for a few hours before it started building a small perch by eating away the leaf and exposing the vein followed by extending that vain with dung pellots.  As this larva grows, the perch also grows and becomes conspicuous to the human eye.  IT IS CRITICAL THAT YOU EXPOSE SECOND INSTAR CATERPILLARS TO 24 HOURS OF LIGHT TO AVOID HIBERNATION!  If your caterpillar does build a hibernaculum, see last three slides.