Eye on Nature: your notes and queries

Foam forms on the shore of Bantry Bay 24 to 48 hours before the arrival of rain. Is there an explanation?
Alec O'Donovan
Bantry, Co Cork

The sea foam in your photographs forms offshore when wind and waves agitate dissolved organic matter, such as river discharges. Winds may be a sign of rain to come, but they and the agitation could occur even when rain is not imminent.

When a caterpillar crawled up to my front door I saw that larvae had erupted from its body.
Phil O'Meara
Baldoyle, Dublin

They are the grubs of the parasitic wasp ‘Cotesia glomerata’, which lays its eggs in the caterpillars of brassica butterflies and moths, in this case the caterpillar of the large white butterfly.

An insect with a tough-looking rear artillery landed on our terrace table.
Alan Moore
Fethard, Co Tipperary

It was the female giant woodwasp, the horntail, 'Urocerus gigas', from your photograph. The "artillery" is an ovipositor. She lays her eggs in pine trunks; after pupating for two or three years they emerge to repeat the cycle.

Michael Viney welcomes observations at Thallabawn, Louisburgh, Co Mayo, or by email at viney@anu.ie. Please include a postal address