Merrifieldia tridactyla, also known as the western thyme plume, is a moth of the family Pterophoridae, first described by Carl Linnaeus in his 10th edition of Systema Naturae in 1758.

It is known from most of Europe, as well as North Africa and Asia Minor.

It is very similar to Merrifieldia leucodactyla Certain identification requires examination of the genitalia.

[2] Adults are on wing from June to July in western Europe.

In Saudi Arabia, larvae have been recorded feeding on the fruits of Cucurbita moschata.