I agree it seems the most likely explanation that the caterpillars have shed their skins and these are what the photograph shows. British ladybird larvae certainly wouldn't cause this kind of damage or prey on caterpillars, and I would have thought it very unlikely harlequin ladybirds or their larvae could attack large caterpillars, even if other food sources are used up.
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The weblog below is for naturalists to use to report interesting sightings, ask questions, report on field meetings and generally post pictures and any information or questions generally relevant in some way to the wildlife and geology of Essex. You will need to register and be logged-on to post to the forum, and you need to upload pictures first, for use in posts. Find out more
The weblog below is for naturalists to use to report interesting sightings, ask questions, report on field meetings and generally post pictures and any information or questions generally relevant in some way to the wildlife and geology of Essex. You will need to register and be logged-on to post to the forum, and you need to upload pictures first, for use in posts. Find out more