Stigmella ogygia
Stigmella ogygia is a moth of the family Nepticulidae. This species was first described by Edward Meyrick in 1889. It is endemic to New Zealand and is found in the North, South and Stewart Islands. This species inhabits the margins of native forest where its larval plant host species are found. Eggs are laid singly on the upper side of the host plant leaf and the larva burrows directly through the bottom of the egg into the leaf-substance. The larvae mine the leaves of Senecio species including Senecio biserratus and Senecio minimus, as well as the leaves of Brachyglottis turneri. The larva emerges from its mine and pupates on the ground near of the larval host plant. Adults are day flying and have been recorded on the wing in March, July and from September to December. There are probably continuous generations throughout the year.
Taxonomy
This species was first described by Edward Meyrick in 1889 and originally named Nepticula ogygia using a specimen collected in Dunedin in January. Morris N. Watt went on to give detailed information about the description and life cycle of this moth in 1921. In 1924 Watt, thinking he was describing a new species, named this species Nepticula erechtitus. In 1928 George Hudson discussed that species under the name Nepticula ogygia and Nepticula erichtitus, and also illustrated a specimen under that latter name, in his book The butterflies and moths of New Zealand. In 1988 John S. Dugdale placed Nepticula ogygia and Nepticula erechtitus in the genus Stigmella. In 1989 Hans Donner and Christopher Wilkinson agreed with this placement in their monograph on New Zealand Nepticulidae and also synonymised Stigmella erechtitus with Stigmella ogygia. This placement was again confirmed in a 2016 revision of the global species placed in the family Nepticulidae. The male holotype is held at the Natural [History Museum, London].Description
EggWatt described the eggs of this species as being bright blue when first laid and as it develops it turns a yellowish colour. They are oval, wafer-like, and flattened against the leaf where it is attached, rounded above. Around the outer margin of the egg the shell is slightly produced so as to form a flattened foot or fringe closely applied to the surface of the leaf. This fringe is a slight degree wider at the micropylar end of the egg.
Leaf mine
The mine is a narrow, usually more or less tortuous gallery, constructed entirely under the upper cuticle of the leaf. The gallery is not a long with its average length ranging from 4 to 6 cm. Its course follows the coarser ribs of the leaf, these and the midrib forming a bar to progress across them. The frass is black and coarsely granular, abundant, and occupies an almost unbroken chain along the middle half or three-quarters of the gallery. However it is entirely absent in the terminal half-centimetre of the mine.
Larva
When full-grown, the larva is very pale green, with a comparatively broad dark-green central line. It has a headpiece of pale amber-brown, darker round external margins, clypeal sutures, and mouth-parts.
Cocoon
Watt described the cocoon as follows:
Pupa
Watt gave a detailed description of the pupa which included the following:
Adult
Meyrick described the adult male of this species as follows:
Watt described a newly emerged specimen of this species as follows:
Watt points out that this species can be variable in appearance with some specimens having a reduced amount of dark irroration in the forewing and the moth appearing to the naked eye as light grey instead of black. At rest the colouration of the adult moth is protective and ensures it is difficult to see.