Pinyon Needle Scale – Matsucoccus acalyptus

Pinyon Needle Scale – Matsucoccusacalyptus

Common Name: Pinyon Needle Scale

Latin Name: Matsucoccusacalyptus


The most commonly observed stage is the second instar nymph, also known as the “bean stage,” which is found attached to needles in early spring. Adult females are black, armoured, portable scales approximately 1/16 inch long that move to the trunk in spring, where they create a cottony mass of eggs. Adult males are winged, fly-like, and infrequently seen in early spring.

Host plant:                                                      


Damages caused by the Pinyon Needle Scale

Adult females and nymphs are feeding, causing needles to become yellow and fall prematurely. Most defoliation occurs on older needles, resulting in a tufted look, with younger needles surviving predominantly on affected trees. Annual infestations can destroy young trees and weaken large trees, making them vulnerable to bark beetle attacks.

Life history and habits:

Pinyon needle scale overwinters as a legless second instar nymph that resembles a tiny black bean. In the early spring, they restart development, moulting to the mobile adult form. Mating takes place in early April. Eggs are placed in vast numbers around the collar, branch crotches, and the underside of larger branches. The egg masses are encased in a white cottony wax that can be extremely visible on strongly affected plants. Newly born nymphs land on needles from the previous year. The second stage emerges in late summer and spends the winter linked to the needle. Each year, there is one generation.