{"id":853,"date":"2025-05-13T14:59:33","date_gmt":"2025-05-13T14:59:33","guid":{"rendered":"https:\/\/sites.rutgers.edu\/nursery-ipm\/?p=853"},"modified":"2025-08-27T19:42:48","modified_gmt":"2025-08-27T19:42:48","slug":"hemlock-woolly-adelgid","status":"publish","type":"post","link":"https:\/\/sites.rutgers.edu\/nursery-ipm\/hemlock-woolly-adelgid\/","title":{"rendered":"Hemlock Woolly Adelgid"},"content":{"rendered":"<h2><strong>Hemlock woolly adelgid (<em>Adelges tsugae<\/em>)<\/strong><\/h2>\n<h4><strong>GDD Window (base 50): 10% of eggs \u2013 150, 50% &#8211; 350, 100% &#8211; 1000; 1001-2200 (nymphs)\u200b<\/strong><\/h4>\n<h5><\/h5>\n<h4><strong>Overview:<\/strong><\/h4>\n<ul>\n<li><span data-usefontface=\"false\" data-contrast=\"none\">Overwinter as wingless adults\u00a0<\/span>\u200b<\/li>\n<li><span data-usefontface=\"false\" data-contrast=\"none\">Lay brownish orange eggs in early spring under the body of the female <\/span><span data-usefontface=\"false\" data-contrast=\"none\">covered in woolly white wax<\/span>\u200b<\/li>\n<li><span data-usefontface=\"false\" data-contrast=\"none\">Reddish brown crawlers hatch in late spring and remain present <\/span><span data-usefontface=\"false\" data-contrast=\"none\">throughout the summer on branch terminals at the base of needles<\/span>\u200b<\/li>\n<li><span data-usefontface=\"false\" data-contrast=\"none\">Crawlers are spread by wind, birds, animals, and humans<\/span>\u200b<\/li>\n<li><span data-usefontface=\"false\" data-contrast=\"none\">Settled crawlers are black with a white fringe around their bodies<\/span>\u200b<\/li>\n<li><span data-usefontface=\"false\" data-contrast=\"none\">Growing adelgids cover themselves in a woolly white wax<\/span>\u200b<\/li>\n<li><span data-usefontface=\"false\" data-contrast=\"none\">Two generations per year<\/span>\u200b<\/li>\n<li><span data-usefontface=\"false\" data-contrast=\"none\">Cause needles to turn grayish-green or yellow, and drop early, branch\u00a0<\/span><span data-usefontface=\"false\" data-contrast=\"none\">dieback, thinning crown, bud and shoot dieback, dieback of major limbs\u00a0<\/span><span data-usefontface=\"false\" data-contrast=\"none\">from the base of the trunk upwards<\/span>\u200b<\/li>\n<li><b><span data-usefontface=\"false\" data-contrast=\"none\">Host plants:<\/span><\/b><span data-usefontface=\"false\" data-contrast=\"none\">\u00a0hemlock (Eastern and Carolina), spruce trees<\/span><\/li>\n<li style=\"list-style-type: none\"><\/li>\n<\/ul>\n<h4><strong>Management:<\/strong><\/h4>\n<h5><strong>Cultural Practices:<\/strong><\/h5>\n<ul>\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"1260\" data-aria-posinset=\"2\" data-aria-level=\"2\"><b><span data-usefontface=\"false\" data-contrast=\"none\">Natural predators:<\/span><\/b><i><span data-usefontface=\"false\" data-contrast=\"none\">\u00a0<\/span><\/i><i><span data-usefontface=\"false\" data-contrast=\"none\">Laricobius <\/span><\/i><i><span data-usefontface=\"false\" data-contrast=\"none\">nigrinus<\/span><\/i><span data-usefontface=\"false\" data-contrast=\"none\">\u00a0beetle<\/span>\u200b<\/li>\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"1260\" data-aria-posinset=\"3\" data-aria-level=\"2\"><span data-usefontface=\"false\" data-contrast=\"none\">Avoid using nitrogen fertilizers<\/span>\u200b<\/li>\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"1260\" data-aria-posinset=\"4\" data-aria-level=\"2\"><span data-usefontface=\"false\" data-contrast=\"none\">Remove nearby birdfeeders, <\/span><span data-usefontface=\"false\" data-contrast=\"none\">birds spread HWA<\/span>\u200b<\/li>\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"1260\" data-aria-posinset=\"5\" data-aria-level=\"2\"><span data-usefontface=\"false\" data-contrast=\"none\">Avoid pruning when eggs and <\/span><span data-usefontface=\"false\" data-contrast=\"none\">crawlers are present<\/span>\u200b<\/li>\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"1260\" data-aria-posinset=\"6\" data-aria-level=\"2\"><span data-usefontface=\"false\" data-contrast=\"none\">Reduce plant stress<\/span><\/li>\n<\/ul>\n<p><strong style=\"color: inherit;font-size: 1.2em\">Materials:<\/strong><\/p>\n<ul>\n<li style=\"font-weight: 400\" data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"540\" data-aria-posinset=\"1\" data-aria-level=\"1\"><b><span data-usefontface=\"false\" data-contrast=\"none\">Contact insecticides:<\/span><\/b><span data-usefontface=\"false\" data-contrast=\"none\">\u00a0<\/span>\u200b\n<ul>\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"1260\" data-aria-posinset=\"2\" data-aria-level=\"2\"><span data-usefontface=\"false\" data-contrast=\"none\">Pyrethroids [3]<\/span>\u200b<\/li>\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"1260\" data-aria-posinset=\"3\" data-aria-level=\"2\"><span data-usefontface=\"false\" data-contrast=\"none\">Carbamate [1A]: carbaryl<\/span>\u200b<\/li>\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"1260\" data-aria-posinset=\"4\" data-aria-level=\"2\"><span data-usefontface=\"false\" data-contrast=\"none\">Glycosides [6]: abamectin<\/span><\/li>\n<\/ul>\n<\/li>\n<li style=\"font-weight: 400\" data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"540\" data-aria-posinset=\"4\" data-aria-level=\"1\"><b><span data-usefontface=\"false\" data-contrast=\"none\">Systemic insecticides:<\/span><\/b><span data-usefontface=\"false\" data-contrast=\"none\">\u00a0<\/span>\u200b<span data-usefontface=\"false\" data-contrast=\"none\">(larvae only, ~June application):\u00a0<\/span>\u200b\n<ul>\n<li style=\"font-weight: 400\" data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"540\" data-aria-posinset=\"4\" data-aria-level=\"1\"><span data-usefontface=\"false\" data-contrast=\"none\">Neonicotinoids\u00a0 [4A]: imidacloprid, <\/span><span data-usefontface=\"false\" data-contrast=\"none\">dinotefuran, acetamiprid<\/span>\u200b<\/li>\n<li style=\"font-weight: 400\" data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"540\" data-aria-posinset=\"4\" data-aria-level=\"1\"><span data-usefontface=\"false\" data-contrast=\"none\">Glycosides [6]: abamectin<\/span>\u200b<span style=\"font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;font-size: 1rem\">\u200b<\/span><\/li>\n<\/ul>\n<\/li>\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"540\" data-aria-posinset=\"7\" data-aria-level=\"1\"><b style=\"font-weight: 400\"><span data-usefontface=\"false\" data-contrast=\"none\">Considerations:<\/span><\/b>\u200b\n<ul style=\"font-weight: 400\">\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"1260\" data-aria-posinset=\"15\" data-aria-level=\"2\"><span class=\"TextRun SCXP242570340 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-usefontface=\"false\" data-contrast=\"none\"><span class=\"NormalTextRun SCXP242570340 BCX0\">Will harm non-target species<\/span><\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<h5><strong>Biorationals:<\/strong><\/h5>\n<ul>\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"1260\" data-aria-posinset=\"2\" data-aria-level=\"2\"><span data-usefontface=\"false\" data-contrast=\"none\">Horticultural oil<\/span>\u200b<\/li>\n<li data-charcodes=\"111\" data-font=\"Courier New,monospace\" data-buautonum=\"8\" data-margin=\"1260\" data-aria-posinset=\"3\" data-aria-level=\"2\"><span data-usefontface=\"false\" data-contrast=\"none\">Insecticidal soap<\/span>\u200b\n<ul>\n<li data-charcodes=\"167\" data-font=\"Wingdings,Sans-Serif\" data-buautonum=\"8\" data-margin=\"1980\" data-aria-posinset=\"4\" data-aria-level=\"3\"><span data-usefontface=\"false\" data-contrast=\"none\">Spray once before egg <\/span><span data-usefontface=\"false\" data-contrast=\"none\">laying begins<\/span>\u200b<\/li>\n<li data-charcodes=\"167\" data-font=\"Wingdings,Sans-Serif\" data-buautonum=\"8\" data-margin=\"1980\" data-aria-posinset=\"5\" data-aria-level=\"3\"><span data-usefontface=\"false\" data-contrast=\"none\">Another spray during <\/span><span data-usefontface=\"false\" data-contrast=\"none\">summer after eggs hatch<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<div class=\"mceTemp\"><\/div>\n<div class=\"mceTemp\"><\/div>\n<figure id=\"attachment_854\" aria-describedby=\"caption-attachment-854\" style=\"width: 174px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-854\" src=\"https:\/\/sites.rutgers.edu\/nursery-ipm\/wp-content\/uploads\/sites\/1396\/2025\/06\/FS751-1-174x300.jpg\" alt=\"\" width=\"174\" height=\"300\" srcset=\"https:\/\/sites.rutgers.edu\/nursery-ipm\/wp-content\/uploads\/sites\/1396\/2025\/06\/FS751-1-174x300.jpg 174w, https:\/\/sites.rutgers.edu\/nursery-ipm\/wp-content\/uploads\/sites\/1396\/2025\/06\/FS751-1.jpg 350w\" sizes=\"(max-width: 174px) 100vw, 174px\" \/><figcaption id=\"caption-attachment-854\" class=\"wp-caption-text\">Settled woolly adelgids at the base of each needle. (See Note below.) Photos Courtesy of James Lashomb and Jianxin Zhang.<\/figcaption><\/figure>\n<figure id=\"attachment_855\" aria-describedby=\"caption-attachment-855\" style=\"width: 300px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-855\" src=\"https:\/\/sites.rutgers.edu\/nursery-ipm\/wp-content\/uploads\/sites\/1396\/2025\/06\/fff17-HWA-2-1-300x225.jpg\" alt=\"\" width=\"300\" height=\"225\" srcset=\"https:\/\/sites.rutgers.edu\/nursery-ipm\/wp-content\/uploads\/sites\/1396\/2025\/06\/fff17-HWA-2-1-300x225.jpg 300w, https:\/\/sites.rutgers.edu\/nursery-ipm\/wp-content\/uploads\/sites\/1396\/2025\/06\/fff17-HWA-2-1.jpg 739w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-855\" class=\"wp-caption-text\">Hemlock woolly adelgids will settle, feed &amp; mature at the petioles of individual hemlock needles. Applying control sprays before they become surrounded by white waxy threads will enhance efficacy. (Photo Credit: John Davidson, UMD Coop. Ext.)<\/figcaption><\/figure>\n<figure id=\"attachment_857\" aria-describedby=\"caption-attachment-857\" style=\"width: 300px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-medium wp-image-857\" src=\"https:\/\/sites.rutgers.edu\/nursery-ipm\/wp-content\/uploads\/sites\/1396\/2025\/06\/fff19-Hemlock-Woolly-Wdelgids-300x216.jpg\" alt=\"\" width=\"300\" height=\"216\" srcset=\"https:\/\/sites.rutgers.edu\/nursery-ipm\/wp-content\/uploads\/sites\/1396\/2025\/06\/fff19-Hemlock-Woolly-Wdelgids-300x216.jpg 300w, https:\/\/sites.rutgers.edu\/nursery-ipm\/wp-content\/uploads\/sites\/1396\/2025\/06\/fff19-Hemlock-Woolly-Wdelgids-768x553.jpg 768w, https:\/\/sites.rutgers.edu\/nursery-ipm\/wp-content\/uploads\/sites\/1396\/2025\/06\/fff19-Hemlock-Woolly-Wdelgids.jpg 800w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-857\" class=\"wp-caption-text\">Canadian hemlock with a heavy infestation of hemlock woolly adelgids. Over the years, the infested hemlocks will typically gradually die-back starting at the base of the tree &amp; working up. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)<\/figcaption><\/figure>\n<h6><\/h6>\n<h6><span class=\"LineBox SCXP56887253 BCX0\"><span class=\"TextRun SCXP56887253 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-usefontface=\"false\" data-contrast=\"none\"><span class=\"NormalTextRun SCXP56887253 BCX0\">Disclaimer<\/span><\/span><span class=\"TextRun SCXP56887253 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-usefontface=\"false\" data-contrast=\"none\"><span class=\"NormalTextRun SCXP56887253 BCX0\"> &#8211; Materials do not cover all possible control scenarios and are intended for licensed professionals. Tradenames do not imply\u00a0<\/span><\/span><\/span><span class=\"LineBox SCXP56887253 BCX0\"><span class=\"TextRun SCXP56887253 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-usefontface=\"false\" data-contrast=\"none\"><span class=\"NormalTextRun SCXP56887253 BCX0\">endorsement and are used as examples. You must strictly follow the label for each compound prior to use. Rutgers is not responsible for<\/span><\/span><\/span><span class=\"LineBox SCXP56887253 BCX0\"><span class=\"TextRun SCXP56887253 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-usefontface=\"false\" data-contrast=\"none\"><span class=\"NormalTextRun SCXP56887253 BCX0\">m is used materials or damages thereof. The label is the law. Labels will provide detailed information on use and restrictions. Additionally, <\/span><\/span><\/span><span class=\"LineBox SCXP56887253 BCX0\"><span class=\"TextRun SCXP56887253 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-usefontface=\"false\" data-contrast=\"none\"><span class=\"NormalTextRun SCXP56887253 BCX0\">application intervals, compatibility, surfactant use, PHI, PPE, important and other key information is described in detail. Always discuss\u00a0<\/span><\/span><\/span><span class=\"LineBox SCXP56887253 BCX0\"><span class=\"TextRun SCXP56887253 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-usefontface=\"false\" data-contrast=\"none\"><span class=\"NormalTextRun SCXP56887253 BCX0\">treatments with your local agents.\u00a0<\/span><\/span><span class=\"TextRun SCXP56887253 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-scheme-color=\"@C00000,,\" data-usefontface=\"false\" data-contrast=\"none\"><span class=\"NormalTextRun SCXP56887253 BCX0\">Note: Neonicotinoids can only be legally applied in commercial agriculture settings by licensed <\/span><\/span><\/span><span class=\"LineBox SCXP56887253 BCX0\"><span class=\"TextRun SCXP56887253 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-scheme-color=\"@C00000,,\" data-usefontface=\"false\" data-contrast=\"none\"><span class=\"NormalTextRun SCXP56887253 BCX0\">applicators.\u00a0<\/span><\/span><span class=\"TextRun SCXP56887253 BCX0\" lang=\"EN-US\" xml:lang=\"EN-US\" data-scheme-color=\"@3B7F23,9,18:76000\" data-usefontface=\"false\" data-contrast=\"none\"><span class=\"NormalTextRun SCXP56887253 BCX0\">Guidelines and recommendations made in this presentation are specific to the state of New Jersey.\u00a0<\/span><\/span><\/span><\/h6>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Hemlock woolly adelgid (Adelges tsugae) GDD Window (base 50): 10% of eggs \u2013 150, 50% &#8211; 350, 100% &#8211; 1000; 1001-2200 (nymphs)\u200b Overview: Overwinter as wingless adults\u00a0\u200b Lay brownish orange &hellip; <a href=\"https:\/\/sites.rutgers.edu\/nursery-ipm\/hemlock-woolly-adelgid\/\" class=\"\">Read More<\/a><\/p>\n","protected":false},"author":3407,"featured_media":856,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[15],"tags":[],"class_list":["post-853","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-pests"],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v23.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Hemlock Woolly Adelgid - Nursery IPM<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/sites.rutgers.edu\/nursery-ipm\/hemlock-woolly-adelgid\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Hemlock Woolly Adelgid - Nursery IPM\" \/>\n<meta property=\"og:description\" content=\"Hemlock woolly adelgid (Adelges tsugae) GDD Window (base 50): 10% of eggs \u2013 150, 50% &#8211; 350, 100% &#8211; 1000; 1001-2200 (nymphs)\u200b Overview: Overwinter as wingless adults\u00a0\u200b Lay brownish orange &hellip; Read More\" \/>\n<meta property=\"og:url\" content=\"https:\/\/sites.rutgers.edu\/nursery-ipm\/hemlock-woolly-adelgid\/\" \/>\n<meta property=\"og:site_name\" content=\"Nursery IPM\" \/>\n<meta property=\"article:published_time\" content=\"2025-05-13T14:59:33+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-08-27T19:42:48+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/sites.rutgers.edu\/nursery-ipm\/wp-content\/uploads\/sites\/1396\/2025\/06\/fff18-Weather-Effects-on-Insects-Mites-Adelgids-1.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"800\" \/>\n\t<meta property=\"og:image:height\" content=\"558\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"Erin O. 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This will provide winter protection &amp; also a place to lay eggs during late winter. (Photo Credit: Steven K. Rettke, Rutgers Coop. 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