The adelgids (genus Adelges) are pear-shaped, soft-bodied green insects with long antennae, closely related to the aphid.

Prominent in appearance, the pineapple or pseudocone gall is often confused with the actual cone of the tree, due to their superficial resemblance.

These adult adelgids may fly to other susceptible conifers, such as larch (Larix), pine (Pinus) and silver fir (Abies alba) or may continue the cycle on the same tree, as some are poor flyers.

[1] They die shortly afterwards, leaving the eggs, which resemble white, cottony twigs, protected beneath their bodies.

In July of the following year winged adelgid appear and fly to the spruces to breed there again, completing the life cycle.

The interior of a bedeguar gall is formed from the bud, and is composed of edible nutritious and structural tissues.

[9] Galls interfere with the natural formation of twigs and cause curling, stunting and the eventual death of new growth.

Individual trees vary in susceptibility to attack; some appear immune, others suffer growth reduction, and some are eventually killed.

[4] Specimen trees in gardens may be afforded a degree of protection by hanging up fat balls to encourage tits which will also feed on the adelgid gall formers.