FOLIAGE LARCH CASEBEARER Coleophora laricella (Hubner) Hosts-- Western larch. Distribution-- An introduced species now found throughout range of host. Damage-- Spring larvae can completely defoliate trees. Defoliated trees can put out another flush of needles, but these may be destroyed by summer larvae. Continued heavy defoliation causes growth loss, branch dieback, and gradual tree death. a Identification-- The tips of mined needles in the spring are straw colored, have a hole in them, and curl over or look wilted (fig. 197a-c). Cases, made from hollowed needle segments, containing larvae may be found on needles or twigs from end of August through following June (fig. 197d). Cases are straw-colored and rectangular, becoming light gray and cigar-shaped during pupation. They are less than one-fourth inch long. In June, when defoliated trees are disturbed, clouds of small, silvery moths (fig 197e) will arise. Eggs are laid singly on needles from late May to early July. Hatching larvae bore into and mine needles. Similar damages-- Larch casebearer damage is most often confused with that of larch needle cast or larch needle blight. Larch sawfly damage is similar from a distance but chewed needles distinguish this damage. Look for distinctive “cases” to identify casebearer. b References-- e See full guide. Figure 197. Larch casebearer larvae extend from protective cases to mine needles (a). As the larvae feed, the hollow needle tips droop (b). Later, the needle tips turn brown (c). Larvae overwinter in cases attached to branch nodes and buds (d). Adult casebearers are tiny moths (e) c d 124 FOLIAGE LARCH DEFOLIATORS COmpaRED Figure 201. This stand of western larch may have been damaged by any of four likely agents. To determine the cause, look closely at the foliage (Table 9). Table 9. Important defoliators of western larch. DISEASE OR INSECT DISTINGUISHING CHARACTERISTICS APPEARANCE Needles red or gray; all needles Needle blight on fascicle droop; round black fruiting bodies on gray needles. Needles yellow- and red- Needle cast spotted; do not droop but will be cast by late summer. Tips of needles droop or kink; Casebearer straw-yellow or red-brown tips; cases of feeding insects on needles or twigs. Needles yellow or red-brown; chunks of needles removed Sawfly by chewing; green larvae with shiny black heads may be present. 127 Identification Keys Figure 2. Comparison of three common types of defoliating insect larvae. 25.