Scientific name: Fiorinia externa Ferris
Native Range: Japan and China
This pest is believed to be introduced from Japan and was first found in New York in 1908. It is currently established in the Eastern United States. It has been intercepted in Minnesota on holiday greenery in 2018 and 2019 but is not established in Minnesota.
Map courtesy: USDA Forest Service, Northern Research Station and Forest Health Protection. “Alien Forest Pest Explorer - species map.” Database last updated 30 July 2019. 11/19/19.
Scales are very small insects that secrete a waxy coating for defense and feed on the sap from plants. They have piercing/sucking mouthparts they insert into the host plant for feeding. Once they begin feeding, most species of scales remain stationary on the plant.
In northern regions, the elongate hemlock scale completes one generation per year; however, two generations per year occur in southern regions. This insect typically overwinters as an egg or a female carrying eggs. The life cycle consists of immobile adults and mobile immatures called “crawlers”. Crawlers are the only part of the life cycle that are capable of dispersing and establishing new populations, and this usually occurs via birds or the wind. The life stages broadly overlap, so crawlers may be found throughout spring and summer. Males and females look quite different because the males have wings.
In the United States, this pest is established in the Atlantic States and sometimes occurs alongside two other exotic pests - a circular hemlock scale (Nuculaspis tsugae) and the hemlock woolly adelgid (Adelges tsugae).
There are a multitude of scale insects that will infest conifers, many of which look very similar. It is important to have the insect properly identified by a specialist.
Elongated hemlock scale is not known to occur in Minnesota at this time and is considered a potential plant pest. For these reasons, the MDA takes steps to prevent the movement of this insect into the state. Items such as nursery stock, Christmas trees, and other holiday greenery entering Minnesota from areas with elongate hemlock scale are inspected to prevent the sale of infested material.
What Can I Do?
Inspect your holiday greenery for elongate hemlock scale. If you find small (~2mm long) yellow-brown parallel-sided spots on the underside of needles, please take a picture and report it to the Minnesota Department of Agriculture (MDA) using the Arrest the Pest Line.
Do your part to protect our environment when the holiday season is over.
Follow this advice:
- Do not toss trees and greenery into backyard woods or your compost pile.
- Use a city/county organized tree and greenery pick-up or burn the greens. Always check with local ordinances first and follow them.