Scale insect of the holm oak

Asterodiaspis ilicicola

Asterodiaspis ilicicola is one species of sucking scale insect from the superfamily Coccoidea that attacks the holm oak; therefore, it can be named scale insect of the holm oak.

The scale insect of holm oak is found on the front side of the holm oak leaves, below a waxy shell as a blister of 1,5-2,0 mm diameter that it segregates. The blister sticks to the leaf through the outside ring. The blister is pale, translucent green color that does not outstand on the dark green of the holm oak leaf. Usually several individuals of the scale insect are found on the same leaf. As a result, the leaf looks as plenty of minute galls, although in fact these are scale insects. The plague spreads at the first stadium of the larva that is mobile. The affected leaves lose vitality, develop black spots and finally they dry and drop, while the tree as a whole loses vitality as well.

The plague of Asterodiaspis ilicicola is widely distributed in the Iberian Peninsula. It parasitizes only the holm oak, mostly its subspecies Quercus ilex ssp.ballota. Its potential damage is serious because it has a high capacity of multiplication and because it affects just the main tree of the Iberian Peninsula, this is the holm oak. [photos Jordi Badia]