Elongate hemlock scale: what the extension services record

This page describes what the named sources say. It is not a diagnosis of any tree and does not say what should be done with one. None of the three pages read lists elongate hemlock scale as a quarantine pest, but NC State Extension says some states regulate its import and the University of Florida abstract carries the keyword regulatory and raises concern about the scale spreading to Florida conifers. Each section names its source, all read on October 9, 2026. The scale has a row in insect pests of trees, which compares it with the other scale insects and caterpillars listed there.

Names and origin

Penn State Extension and NC State Extension both give the scientific name Fiorinia externa, and Penn State adds that it is sometimes known as the fiorinia scale. The University of Florida publication (Dale, Birdsell and Sidebottom, 2019) calls it an armored scale native to Japan and eastern Asia. All three give 1908 for the first United States record: Penn State and the Florida abstract name Queens, New York, and NC State says New York City. NC State says the scale was slow to spread until the mid-1970s and then greatly expanded its range.

Hosts

Penn State lists eastern hemlock, Carolina hemlock and northern Japanese hemlock as principal hosts, with fir and spruce. It also names cedar, Douglas-fir, pine and yew, but calls these not preferred and says they are usually growing next to infested hemlocks. NC State says hemlocks and true firs, including Fraser fir, are the most common hosts in western North Carolina, and that blue spruce and blue atlas cedar are occasionally attacked but seldom damaged much. The Florida abstract names hemlocks and firs as the primary hosts and says neither grows in Florida.

Where the sources place it

Source	Places named	Other status wording
Penn State Extension	Connecticut, Maryland, Massachusetts, New Jersey, New York, Ohio, Rhode Island and Virginia, and Pennsylvania as the state the page is written for.	Called a serious armored scale pest of ornamental and forest hemlock in Pennsylvania.
NC State Extension	More than 14 states in the eastern United States, as far south as Georgia. First found on Fraser fir Christmas trees in Yancey County, North Carolina, in August 1993.	Some states regulate its import, and shipments to other countries must be free of the scale.
University of Florida IFAS (EDIS, 2019)	Most of the eastern United States.	Concern that scale arriving on cut Christmas trees may establish on Florida conifers, including the endangered Florida torreya and Florida yew.

What the scale looks like

Penn State describes the adult female cover as flattened, elongate, light yellow brown to brownish orange and 1.5 mm long, on the lower needle surface and on new cones. The male cover is white and smaller, and Penn State says waxy strands from settled crawlers can build up until the underside of needles looks white, which it says can be mistaken for hemlock woolly adelgid. NC State agrees that the scale is longer than wide, males white and females brown, and that crawlers and immature scales are yellow and not elongated. It says as many as 30 scales can sit on one needle, sometimes on top of each other, mostly on the underside and across several years of growth. For the adelgid itself see hemlock woolly adelgid.

Life cycle as the sources state it

Penn State says the scale overwinters as fertilized females or eggs, that females lay eggs under their covers from early spring into early summer, and that one female may produce a total of 20 eggs. Eggs hatch in three to four weeks into crawlers, which Penn State says spread by wind or on the feet or plumage of birds. NC State describes a different pattern for the southern Appalachians: two overlapping generations, so that all stages can be found almost any time of year, with peak crawler emergence from late May into June. It gives 12 to 16 eggs at a time, eggs produced six to eight weeks after mating, hatching within a month, and about 16 weeks from crawler to the next generation of crawlers. Both say winged males mate with the females. NC State says the males live only a few days, Penn State says adult females may live up to one year and NC State says more than a year.

Damage as the sources describe it

Penn State says the scale feeds on the contents of needle tissue, that needles develop yellow banding on top, drop early and leave the crown thin, and that an infestation weakens trees so that secondary organisms such as the hemlock borer or Armillaria root rot can attack. It says the scale is often found on the same tree as hemlock woolly adelgid. NC State describes yellow blotches and stunted growth under heavy infestation, more commonly the white wax of maturing males on upper needle surfaces in summer, and says an infestation that does not reduce growth can make a Christmas tree unsaleable. See Armillaria root rot for that disease.

Natural enemies and status

Penn State names two small parasitic wasps, the lady beetle Chilocorus stigma and several lacewings. NC State names the wasp Encarsia citrina, says the scale was once considered self-limiting in forest hemlock stands for that reason, and says parasitized scales show a hole in an otherwise empty shell. Neither page names a report line. This page gives no treatment steps, product names, rates or timings. For who may apply pesticides see pesticide licences.