Identifying Invasive Species – The Hemlock Woolly Adelgid

The Hemlock Woolly Adelgid has been causing the increased mortality of Eastern Hemlocks throughout the East coast of the United States since 1951 (Orwig and Forester 1998). The Hemlock Woolly Adelgid attacks individual hemlock needles, interrupting the flow of nutrients, causing discoloration, loss of foliage, and the eventual death of the hemlock tree in just 4-10 years.

The pest surrounds itself with a white cotton-like coating, which is only visible twice a year in the Spring and Fall. This coating is currently the only method of diagnosing the spread of the infestation. Spectral Evolution has been fortunate to work with ecologists and foresters to see how field spectroscopy might aid in diagnosing the presence of the HWA infestations on a larger scale. In preliminary assessments, we were able to identify distinguishing features of the cotton-like coating at 1731nm, 1759 nm, 2312 nm, and 2351 nm (see figure 1) by using two field Spectroradiometers.

The pest surrounds itself with a white cotton-like coating, which is only visible twice a year in the Spring and Fall. This coating is currently the only method of diagnosing the spread of the infestation. Spectral Evolution has been fortunate to work with ecologists and foresters to see how field spectroscopy might aid in diagnosing the presence of the HWA infestations on a larger scale. In preliminary assessments, we were able to identify distinguishing features of the cotton-like coating at 1731nm, 1759 nm, 2312 nm, and 2351 nm (see figure 1) by using two Spectral Evolution field Spectroradiometers.

Figure 1

After identifying these specific HWA characteristics, the next step was to see what a more representative sample of the HWA infestations on a twig would look like (figure 2). In these scans, the cotton-like coatings were still distinguishable in the same spectral regions. Further research will be conducted using canopy measurements during varying levels of infestation to characterize HWA presence.

Figure 2

At Spectral Evolution, we provide various instruments for vegetation remote sensing applications, like invasive species monitoring. Each has specific field operational capabilities to provide the best data for your campaign.

The PSR+ is a robust field spectroradiometer that features built-in memory to collect your scans. This allows for standalone use, negating the need for a handheld device or computer to operate.

Spectral Evolution’s ultra-high-resolution SR-6500 spectroradiometer features high-density photodiode arrays and enhanced stability to provide the best spectral resolution for in situ remote sensing applications.

Our RS-8800 spectroradiometer is the only instrument that comes with the Sensaprobe™ phone grip, which provides real-time feedback as you are scanning. This accessory allows you to see an image of your fiber’s field of view. It also indicates the angle of the probe and sun and provides your GPS location, allowing you to keep more detailed notes on each scan.