Posted: 14/08/2012 at 09:35
Not sure that these caterpillars will harm your chicks, but to answers your query I googled this:
"Contains the alkaloid buxine which causes nausea vomiting & diarrhoea. The leaves are poisonous to humans but its unpleasant odour and bitter taste tends to minimise its ingestion. Farm stock especially cattle are said to have grazed box bushes if they get into gardens. Death may occur through respiratory failure."