The roles that leaf quality, the presence of siblings, trails, vision
and touch play in reaggregation by imported willow leaf beetle larvae
were examined. Larvae responded positively to the presence of siblings
, their secretions, and faeces while reaggregating. Larvae do not have
to see or touch siblings in order for reaggregation to occur and leaf
quality does not appear to be involved in reaggregation. There were d
ifferences in behaviour of 4- and 8-day-old larvae: 4-day-old larvae r
esponded positively to the presence of siblings whereas 8-day-old larv
ae did not, and under natural conditions 4-day-old larvae are found in
aggregations whereas 8-day-old larvae are solitary. (C) 1995 The Asso
ciation for the Study of Animal Behaviour