▁to ▁a ▁weak ▁imm une ▁system ▁for ▁the ▁F ras er ▁f irs ▁and ▁making ▁them ▁more ▁sus cept ible ▁to ▁the ▁b als am ▁w ool ly ▁ad el g ids . ▁The ▁Spr uce - fir ▁m oss ▁sp ider , ▁which ▁lives ▁on ▁m oss ▁m ats ▁below ▁the ▁forest ▁can opy , ▁is ▁considered ▁end anger ed ▁due ▁to ▁the ▁decl ine ▁of ▁the ▁F ras er ▁fir . ▁ ▁The ▁B als am ▁w ool ly ▁ad el g id ▁also ▁has ▁a ▁significant ▁impact ▁on ▁Pacific ▁North west ▁for ests . ▁Specifically , ▁grand ▁fir , ▁silver ▁fir ▁and ▁sub al pine ▁fir ▁in ▁Washington ▁and ▁Oregon ▁all ▁can ▁serve ▁as ▁a ▁host . ▁Ext ensive ▁mort ality ▁due ▁to ▁this ▁p est ▁in ▁the ▁Cas cade ▁Mountain ▁range ▁was ▁recorded ▁during ▁the ▁ 1 9 5 0 s ▁and ▁ 1 9 6 0 s . ▁Land ▁area ▁affected ▁by ▁the ▁ad el g id ▁in ▁the ▁Pacific ▁North west ▁has ▁increased ▁from ▁ 8 3 , 3 2 5   ac res   ( 3 3 7   km 2 ) ▁in ▁ 2 0 0 4 ▁to ▁ 1 0 8 , 1 2 8   ac res   ( 4 3 8   km 2 ) ▁in ▁ 2 0 0 5 . ▁ ▁References ▁ ▁Category : Ad el g idae ▁Category : In sect ▁p ests ▁of ▁temper ate ▁for ests ▁Category : H em ip tera ▁of ▁Europe ▁Category :