Adelgidae
Taxonomic placing: Insecta, Hemimetabola, Hemiptera, Sternorrhyncha, Aphidoidea.
Common name: Woolly conifer aphids, pine aphids, spruce aphids.
Geographical distribution: This family, which consist of about 70 species, occurs mostly in temperate zones.
Host plants: Pines (Pinaceae) (conifers).
Morphology: The soft, reddish pear-like body is about 4-7 mm long, sometimes covered with woolly wax and with short antennae. Although related to the aphids (Aphididae), adelgids bear neither a cauda nor siphunculi. Their eggs are covered by white fluffy wax.
Life history: Adelgids infest only pines. Their life cycles may be holocyclic, with a sexual generation and host alternation, or anholocyclic, entirely parthenogenetic, without migrating from the primary to a secondary host (e.g. host alternation). Species of spruce (Picea spp.) are the primary hosts, and other conifers, like Abies, Tsuga or Pinus are the secondary hosts. Adelgids are oviparous and an entire cycle may require two years to complete.
Economic importance: Adelgids feed by sucking out plant components with their long mouthparts. Many species produce galls or other leaf distortions on spruce. Some species, such as the balsam wooly adelgid, Adelges piceae (Ratzberg) and hemlock woolly adelgid, A. tsugae Annand, are capable of killing trees within a few years after infestation. Pineus pini (Macquart) causes severe damage to pines in Turkey.
Management
Horticultural methods: The removal of infested, weak tree parts and planting non-hosts trees.
Chemical control: Organophosphates may be applied, but usually only in nurseries.
Biological control: Successful control of adelgids has been achieved in different regions with predatory Anthocoridae, Coccinellidae, and Chamaemyiidae.
References
Havill, N.P. and Foottit, R.G. 2007. Biology and evolution of Adelgidae. Annual Reveviw of Entomology 52: 325–49.
Sanyang, F. and Shanchun, Y. 1997. The conifer woolly aphids (Adelgidae) in China. Journal of Forestry Research 8: 30-32.
Zilahi-Balogh, G., Kok, L.T. and Salom, S.M. 2002. A Review of world-wide biological control efforts for the family Adelgidae. Hemlock Woolly Adelgid in the Eastern United States Symposium, 129-140.
https://www.google.co.il/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=Adelgidae