Elongate Hemlock Scale

Elongate Hemlock Scale seems to be exploding this year over most Christmas tree farms in Mitchell County. The treatment window for this summer is getting close to closing so now if the time to be out scouting and evaluating the amount of infestation you have from Elongate Hemlock Scale.

The elongate hemlock scale, sometimes known as the fiorinia scale, is a serious armored scale insect pest of hemlock and Fraser fir. It is believed that this armored scale insect was unintentionally introduced into the United States from Japan.

The EHS is found almost exclusively on the underside of needles and will be found on multiple years of growth. On infested branches, scale numbers average 10 per needle and there can be as many as 30 on a single needle with scales sometimes found on top of each other.

When infestations are heavy, trees may have yellow blotches or patches on the needles and growth will be stunted. However, such symptoms are not commonly seen on Fraser fir in western North Carolina. More commonly what is seen are the white, waxy excretions of the male scales found on the upper surface of needles especially during summer months when males are maturing. Infestations that do not reduce tree growth can still make trees un-saleable because of this white covering to the needles.

The EHS has two, overlapping generations in the southern Appalachians. Because of this overlap, all life stages can be found almost any time of year, though proportions of one stage to another will vary. Crawlers emerge throughout the growing season and even in winter months, but peak crawler emergence is in May into June and again in late October into November.

The crawlers must find an appropriate feeding site. Crawlers may move somewhere else on the same needle, crawl onto the new growth, or move passively through wind or bird movement onto other trees or fields. Once a feeding site is found they molt, never moving again.

Immature scales appear to burrow under the waxy layer produced by the needle, making them even more protected against pesticide applications and predators. As the scale matures, it forms behind the original yellow immature, making it look as if a smaller scale is attached to a larger. The feeding tube of the immatures is as long as it is, appearing as a tiny coppery wire. The scales feed in epidermal cells.

Immature female scales go through three stages of development while males have additional prepupal and pupal stages. Males emerge as a tiny winged insect with large black eyes and long antennas. Before they emerge, they can sometimes be found under the white cotton of the pupal stage. They have no mouth-parts and live only a few days, mating with females. Eggs are produced six to eight weeks after mating. Each female produces 12 to 16 eggs at a time, which hatch within a month. Mature females may live for more than one year.