November 2005. This is not a pest story, but while a member was hiking in Samoa, a gleam of light caught his eye in the forest. When he tracked it down, it turned out to be a glob of gel attached to a fern frond. In the frond was the larva of an insect. The mass of the gel was many times greater than that of the larva, and it did not look as if the glob had come from the fern. The most likely scenarios, were (1) the insect produced the glob as protection; (2) the glob fell from a tree and trapped the insect; (3) the fern produced the glob and trapped the insect; or (4) the larva was trapped in a glob of ectoplasm. Can anyone identify this insect or its glob?
Some suggestions were given:
1) The larva of a nematocerous Dipteran – craneflies or “daddy long legs” type of fly. The ?Tipulid larva lives inside the gel – it probably feeds on algae/fungi on the leaves – in the damp forest. It is unlikely the gel was produced by the fern as the leaves don’t show any damage. Quite how it feeds, was not known, but this family has a whole range of larval habits; some live in streams, others in soil, and some are horticultural pests, e.g., cranefly larvae.
2) The larva is a moth caterpillar. Caterpillars in the Cook Islands do not secrete a protective glob, therefore, it may be trapped. It is difficult to see if the larva is still eating on the edge of the pinna, but even if it is continuing to feed it could still just be trapped. A member reported seeing a small grasshopper trapped in a bubble of water on a taro leaf and maybe this is similar. As to how there was such a large blob of gel sitting on the fern, there was no suggestion, although a member said that sometimes globs of gel are seen on Angiopteris where a pinna has broken off.
3) An image of the other glob that might be seen in the forest. The larva of the spittlebug sucks sap and expels it undigested as a sugary liquid. It then blows air into it to make a protective foam. The one in the photograph (right) is the Rarotonga Spittlebug, but there are similar ones in Samoa.