Description of the mite

• The females adult of Panonychus ulmi , octopods and globular in shape, are clearly visible to the naked eye on the green leaf blade (size approximately 0.5 mm). They are dark red in color, with 2 rows of white dorsal tubercles each carrying a white bristle. We can also distinguish the presence of 2 anterolateral red eyes on the prodorsum. The very agile males are distinguished from the females by their fusiform shape, their smaller size and their orange color spotted with black, on which little or no protuberances are observed.

• The egg has a variable color according to the seasons: brick red in winter, light red in spring and summer. It is spherical in shape, slightly ridged with a characteristic long apical point. Its size, 1/10 of a mm in diameter, makes it difficult to observe with the naked eye.

• The larva is red to bright orange in color. The first larval instar is hexapod while the following are octopods. The moulting stages are more or less bright red in color.