Odd Tracks

This odd pattern that has shown up on polyethylene irrigation tubing was sent in by an observant Santa Paula grower.  The fruit trees were covered with aphids and there was sooty mold growing on the honey dew dripping onto the tubing. Such a beautiful pattern, but what causes it? 

Turns out Mark Hoddle, Biocontrol Specialist at UC Riverside had an answer - snails.  Brown garden snails are active with this warm, wet weather and they are enjoying feeding on the sweet taste of honey dew. 

The bottom side of the snail has a mouth composed of raduli which are sharp teeth which scrape along the surface of the tubing, leaving marks.

All images from Los Angeles Natural History Museum - https://nhm.org/stories/microscopic-look-snail-jaws

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