Published online by Cambridge University Press: 10 July 2009
The volcanic island of Anak Krakatau emerged from the sea in 1930. The antlion Myrmeleon frontalis has only become established on Anak Krakatau within the last five years, despite having been present on the other Krakatau Islands for at least 50 years.
The appearance of the antlions on Anak Krakatau seems to have coincided with the construction of a shelter hut in 1986 which provides a suitable under-floor habitat of dry dusty soil for the larvae to construct their pits. From the hut site they have extended into sub-optimal locations around the bases of clumps of wild sugarcane, Saccharum spontaneum, on the adjacent lower slopes of the outer cone ash fields.
The soil around the Saccharum chimps is variable. Fine deposits are suitable for antlion larvae, more gravelly soils are not. The antlion larvae inhabiting the Saccharum clumps are disturbed by rain which destroys their pits.
These two habitats, the hut and Saccharum sites, are the only places on the island that are occupied by the antlion larvae. They have quite different micro-climates so that the two populations are out of synchrony with each other.