For food, Empoasca vitis stings its host plants in search of the elaborate sap that constitutes its source of nutrients. The puncture damages the tubes sifted by the mechanical action of the stylet (mouthpiece of the insect) and not the cells of the mesophyll, which has the effect of blocking the sap produced.

 

Thus, the mechanical injuries of the vessels of the bast cause leaf discolorations: a more or less marked reddening for the black grape varieties or a yellowing for the white grape varieties.

 

The discoloration begins at the periphery of the blade, it is blocky in shape and is delimited by the veins. The blade tends to curl slightly. Subsequently the leaves become necrotic and dry out.

 

During water stress conditions, the symptoms are accentuated which results in a decrease in photosynthetic activity. These symptoms can be spectacular but are not very damaging according to all the studies that have been carried out so far.

 

• Berries and twigs

It should be noted that this leafhopper can cause indirect damage during a major attack, with the consequence of slowing down the ripening of the berries, a quantitative loss of harvest, as well as bad wood growth.