Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Practical tables for determining the principal forms of the Chermesidae (= Adelgidae) of France.

Abstract

Adelgids are now serious pests of conifers in France, causing galls and twisted branches and generally weakening trees by removing sap in large quantities, and correct identification of the species concerned is often essential for adequate control. Detailed information is given on the population dynamics and complicated life-cycle of these insects, including the parallel cycles carried on simultaneously, in a single species, by non-migrating populations on the primary food-plant (spruce) and by migrating populations on secondary food-plants (pine, fir and larch). Some of the different forms of adelgids appearing during the course of the cycles, and the types of malformation caused on Picea spp., are illustrated. Tables are appended in which the species and forms of adelgid can be identified from various criteria including the plant part and species attacked, time of year when attack becomes visible, type of gall and date of its opening, and egg colour and other morphological characteristics of the insects. Attention is drawn to the fact that the so-called 'classic' names are retained in this paper for these French adelgids (or chermesids) even when these names are not currently valid in order to avoid the confusion caused by the frequent name changes that have recently occurred in this insect family.