Common Bluebottle

The Graphium sarpedon, commonly referred to as the Common Bluebottle, is a species of swallowtail butterfly belonging to the family Papilionidae. While celebrated for its striking blue markings, the larval stage of this insect can act as a pest, causing notable damage to specific ornamental and evergreen trees in its native range.

The primary hosts for the larvae of this species are members of the Lauraceae family. Cinnamomum camphora (camphor tree) and various laurel species are particularly susceptible. In urban and nursery environments, infestation can lead to the widespread consumption of foliage, affecting the vigor of young host plants.

The biology of the species involves a rapid life cycle, especially in warmer climates. Eggs are laid singly on the underside of leaves. The larvae progress through five distinct instars, feeding voraciously throughout their development. Pupation occurs on the host plant or nearby structures, with the pupa often mimicking twigs to avoid predation.

The damage caused by Graphium sarpedon is primarily foliar. Young larvae create small holes in the leaf surface, while mature caterpillars can strip entire branches of their leaves. Heavy infestations result in significant defoliation, which stunts growth and reduces the aesthetic appeal and commercial value of nursery stock.

Effective management strategies include cultural and biological controls. Routine inspection of host trees during the growing season is crucial for early detection. Manual removal of caterpillars is highly effective for small-scale gardens. For more severe infestations, the use of biological insecticides containing Bacillus thuringiensis (Bt) provides a targeted and environmentally friendly solution.