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Fairy Moth - Adela trigrapha - female

Fairy Moth - Adela trigrapha - Female
Edgewood Preserve, Santa Clara County, California, USA
April 15, 2010
Size: ~18-20 mm (wingspan)
Found in association with black-crowned Adelids presumed to be A. trigrapha. This type has shorter antennae (about 1.5X wing length instead of 2.5X) and a red-orange crown; I do not discern any difference in the width of the forewing stripes. The red morph was also less abundant than the black, maybe about 1/5 of the large number that were present that day. Also, the black-crowned's were actively nectaring on newly opened Linanthus, while the red-heads seemed content to rest with wings folded, on blades of grass.

Either we have two moths here or the species is gender dimorphic.

Black-crowned morph:

Moved from Adela.

The short antennae tell us this is female. Most Adela exhibit this dimorphism with the female having shorter antennae. In A. trigrapha the female has a red crown and a more shiny/purple color. Up in the Sierra - males of A. eldorata can also have red.

Looks Like 0225 - Adela trigrapha (fem.)
This is a sexually dimorphic species. Chris Grinter specimen photos at Moth Photographers Group.