''Adelges'' is a genus of insects which feed on

conifer Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...

s. They have complex life cycles, some species feeding exclusively on

spruce A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Northern hemisphere. ''Picea'' ...

, others feeding on spruce and an alternate

. However,

gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or war ...

s characteristic of each species are formed only on spruce. Six generations are usually needed to complete the 2-year cycle, and in the case of species having an alternate host, winged adults about 2 mm long are formed only in the generations that move from one host to the other. The spruce gall adelgid (''Adelges lariciatus'' Patch) occurs in alternate years on spruce and larch from Alberta to the Maritimes and in adjacent parts of the United States. The pale spruce gall adelgid (''Adelges strobilobius'' Kaltenbach) has a similar range but prefers

black spruce ''Picea mariana'', the black spruce, is a North American species of spruce tree in the pine family. It is widespread across Canada, found in all 10 provinces and all 3 territories. It is the official tree of Newfoundland and Labrador and is tha ...

red spruce ''Picea rubens'', commonly known as red spruce, is a species of spruce native to eastern North America, ranging from eastern Quebec and Nova Scotia, west to the Adirondack Mountains and south through New England along the Appalachians to wester ...

white spruce White spruce is a common name for several species of spruce (''Picea'') and may refer to: * '' Picea engelmannii'', native to the Rocky Mountains and Cascade Mountains of the United States and Canada * ''Picea glauca ''Picea glauca'', the whi ...

. Species include: * ''Adelges abietis'' (

Pineapple gall adelgid The pineapple gall adelgid (''Adelges abietis'') is a species of conifer-feeding insect that forms pineapple-shaped plant galls on its host species, commonly Norway and Sitka spruce. The adelgids (genus ''Adelges'') are pear-shaped, soft-bodie ...

) * ''Adelges cooleyi'' (

Gall adelgid The gall adelgid (''Adelges cooleyi'') is an adelgid species that produces galls in spruce trees. They infect the new buds of native spruce trees in the foothills of the Rocky Mountains in the spring. They also attack blue spruce to a lesse ...

) * ''Adelges piceae'' (

Balsam woolly adelgid The balsam woolly adelgid (''Adelges piceae'') is small wingless insect that infests and kills firs. In their native Europe they are a minor parasite on silver fir and Sicilian fir, but they have become a threat especially to balsam fir and ...

) * ''Adelges tsugae'' (

Hemlock woolly adelgid ''Adelges tsugae'', the hemlock woolly adelgid () or HWA, is an insect of the order Hemiptera (true bugs) native to East Asia. It feeds by sucking sap from hemlock and spruce trees ('' Tsuga'' spp.; '' Picea'' spp.). In its native range, HWA ...

)

References

Bugguide.net. Genus ''Adelges''
Adelgidae Sternorrhyncha genera {{Sternorrhyncha-stub