Morova gall habitat
OVAL swellings, called galls, are usually present in the stems of the native vine
Muehlenbeckia australis, abundant around Dunedin. These galls are made by a moth,
Morova subfasciata.
Just before the caterpillar pupates, it bites almost through the gall, leaving a transparent window. Enemy eyes look through the window, often those of the parasitic ichneumonid wasp
Diadegma muelleri, which lays eggs in the gall. The ichneumonid larva eats the moth chrysalis then spins its own rough darkbrown cylindrical cocoon, and the resulting ichneumonid wasp escapes from the round exithole just as the moth would have done, leaving the hole open for a host of new occupants. Sometimes a steelblue tachinid fly, Pales sp., emerges from the cocoon.
Often one of the first new occupants of the gall is the strange beetle Lemidia aptera, whose larvae feed inside on the living walls.
After the walls become dry, spiders, solitary wasps, and bees nest in them. The spider
Clubiona huttoni often lays eggs within silken cocoons in the galls. There, a peculiar spiderwasp Epipompilus insularis sometimes rushes in and lays its egg on the spider. Within two weeks, the spider is entirely eaten by the spiderwasp larva, which spins a pale buff cocoon inside the spider’s silken cocoon. (All other New Zealand spiderwasps transport paralysed spiders to another nest site.) In dry galls, solitary bees
(Hylaeus species) secrete transparent cellophanelike waterproof cell linings in which they make a pudding of pollen and nectar and lay an egg on top.
Sphecid wasps fill the galls with paralysed spiders and insects. These solitary wasp and bee larvae are eaten in turn by tiny parasitic wasps
(Melittobia species), which easily tunnel through mud seals made by the sphecid wasps. Scale insects, native book lice, many other native insects, and pseudoscorpions occur in these galls; the interesting succession of occupants going on in the same galls for years.