Step 1
Bagworms ( Thyridopteryx ephemeraeformis ) infest arborvitae May through the heart of June . These plague are identified through their larva ’s silken bags that hang from limb . Infused with industrial plant fabric , the dish are often slip as part of the plant . At maturity , the bags can arrive at 1 inch long . Females will remain in the bag their entire lives , while males will come forth as a dark moth with clear wings . Check for and destroy bags throughout the year . pesticide can be effective when bags are little , although a second software is give notice two week after initial spray .
Step 2
Arborvitae Leafminer
Arborvitae leafminer ( Thyridopteryx ephemeraeformis ) is a silver - gray moth , generally 1/3 inch long . Signs of an infestation include yellow or brown backsheesh on leafage , especially on the south side of the flora . Larvae feed on the lead of arborvitae through the give and emerge as adult in June and July . Remove tips by paw for tripping infestation ; spray with a systemic insecticide in recent fall or former springtime for laborious infestations .
Strawberry Root Weevil
The hemangioma simplex root weevil ( Otiorhynchus ovatus ) favor arborvitae over other evergreens . wilt and dieback of subdivision are common symptoms of an infestation . Since the adults tip near folio margin , notching also indicates weevil . To pop adult beetle before they lay testicle , use foliar insecticides in July . Larvae overwinter in the soil and feed on root , and the fungi Beauveria bassiana and entomophagous nematodes are effective controls when applied to the soil in early August . The University of Minnesota Entomology section urge keep soil moist to ensure potency .
Fletcher Scale
Though arborvitae is not a favourite of fletcher musical scale ( Parthenolecanium fletcheri ) , it can fall victim to this pest . Signs of an infestation include yellowing needles , premature phonograph needle drop and a black pitchy mold growth . Eggs hachure mid to late June , although the round , brown adult female may arrive as ahead of time as April , often clustering where leafage join branches . apply horticultural oil colour to smother reveal egg , and abeyant immature grownup . Systemic insecticide also protect arborvitae .
Spruce Spider Mite
natty wanderer mites ( Oligonychus ununguis ) may be difficult to see with the raw optic , but their personal effects are readable . jaundiced or bronze leaves , foliage drop and offset dieback are symptoms of an infestation . A canvass of paper support under a branch while shaken will affirm spider tinge . A dormant fossil oil spray in the fall will remove mites without damaging their instinctive predators .
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