DAYTIME MECHANISMS OF REAGGREGATION IN IMPORTED WILLOW LEAF BEETLE, PLAGIODERA-VERSICOLORA, LARVAE (COLEOPTERA, CHRYSOMELIDAE)

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