Michael Viney answers a selection of queries on nature
I remember seeing luminous little lights in muddy places, while feeding cattle in a cut away bog at night time during the winter. My father referred to these as "Jacky the Lantern", and the local folklore was that these would lead you astray at night. - A Cronin, Lissivigeen, Killarney, Co Kerry
One type of luminescence in soil is given off by bacteria called Photorhabdus luminescens, which lives in symbiosis with a tiny transparent nematode (round worm), a millimetre long, of the Heterorhabditis family. The nematode enters the circulatory system of an insect or larva and expels the bacteria from its intestine which infect the host, proliferating until they kill it. The bacteria feed on the dead host and begin to glow, giving off an eerie light. The nematode reproduces inside the cadaver and the hatched young feed on the bacteria that are feeding on the dead host. When the nutrients from it run out, the young nematodes stop eating the bacteria and take them into their intestines. They then leave the cadaver and return to the soil to begin the cycle. Radon gas in soil becomes phosphorescent below freezing point. It would be present only in granite areas.
Send observations to Michael Viney, Thallabawn, Carrowniskey PO, Westport, Co Mayo; e-mail: viney@anu.ie (include a postal address)