Automatic Garden Waterer
http://tinkeringetc.blogspot.com/2012/08/automatic-garden-waterer-part-2.html
Therein lay the evolutionary problem confronting ladybird beetles, whose larvae were highly vulnerable to ant attack.
To avoid being killed as they poach the ant's scales, ladybird larvae evolved to produce two anti-ant defences: an impregnable woolly coat of wax filaments, and glands which produce defensive chemicals. Most of the ladybird family's 6,000 species are found in lineages with one or both of these defences.