Less often , they are found on hemlocks ( Tsuga ) and firs ( Abies ) .
They are specialists on conifers , attacking many species of pine ( Pinus ) and spruce ( Picea ) .
Less often , specialists are found on hemlocks ( Tsuga ) and firs ( Abies ) .
They are specialists on conifers , attacking many species of pine ( Pinus ) and spruce ( Picea ) .