A unique characteristic of A. hupeiensis is the unusual circling behavior that resembles a hurricane with an “eye” in the center. When observed on the University of Illinois campus on April 21, 1999, the worm circle was approximately 1.5-2 meters in diameter, and moving in a clockwise direction. This circling behavior occurs on sidewalks underneath an overhead light. Also, every light was adjacent to grass that had a group of worms below it. This behavior suggests that the worms are attracted to lights (Zaborski and Gittenger, 2001).
Another behavior seemingly unique to this worm is the observation of the worms curling in a tight coil when removed from the soil and handled (Zaborski and Gittenger, 2001).
There have yet to be studies about how best to manage A. hupeiensis. Because it seems to be a generalist species (able to survive and thrive in many different types of environments), the worms are likely not a conservation priority. Conservation activities instead may focus on how to control this species outside of its natural range.
Amynthas hupeiensis is commonly known as the “stinkworm” and “greenworm” (Redmond et al., 2014; Zaborski and Gittenger, 2001). A. hupeiensis is found in: Korea, Japan, Taiwan, China, New Zealand, Kinmen Island, and North America, including more than 17 states in the United States (Michaelsen, 1895; Zaborski and Gittenger, 2001). Whereas A. hupeiensis is native in the majority of Asia, it is considered an exotic species in the United States (Redmond et al., 2014; Zaborski and Gittenger, 2001). Zaborski and Gittenger (2001) mention that the worm is native to areas of East Asia such as Japan, China, Korea, and Taiwan. Its large distribution is supported by Huang et al. (2007), who found that A. hupeiensis has a wide range across China. Contrary to this finding, Tsai et al. (2000) states that A. hupeiensis is an exotic species in Taiwan, and concurs with its distribution in China, Ryukyus, Japan, Korea, and Southeast Asia. This worm is one genus in the family Megascolecidae. The Megascolecidae is dominant in China, with a total of 243 species found in one study (Huang et al., 2007). Out of these 243 species, 163 species were of the Amynthas genus.
In China, A. hupeiensis was observed to be most common in agroforestry plots, rice paddy field margins, and vegetable field margins compared to the other plot types that were observed (including lawn on the dike, rain-fed floodplain, rain-fed paddy field, commercial vegetable field, and home garden). However, the highest density of worms in this study was seen in home gardens, and the highest percentage of adult stink worms with clitellate were observed in the vegetable field margins (Fang et al., 1999). In Korea, the stink worm was commonly found in or near rice paddy fields in Korea (Blakemore and Lee, 2013). Fang et al. (1999) found that there was a positive correlation between clay and lime content in the environment and the worm population density, and a negative correlation between the population density and the percentage of sand in the soil (Fang et al., 1999).
This worm has been used as a bioindicator for detecting heavy metal accumulation (copper, cadmium, and zinc) in the soil. A study done by Wang et al. (2009) focused on the ecological quality of Chinese agricultural plots after mining ceased. A. hupeiensis was found in only two of ten plots at lower levels of contamination, indicating that this species is sensitive to this specific type of contamination. On the contrary, another study documented that A. hupeiensis was more tolerant of heavy metal toxin accumulation in the soil than other earthworm species (Na et al., 2011). A. hupeiensis was found in the following materials four and eight years after yearly application: pig manure compost, municipal sewage, alcohol fermentation processing sludge, leather processing sludge and industrial sewage. Toxins within these materials included chromium, lead, nickel, copper, zinc, and cadmium (Na et al., 2011).
Length of A. hupeiensis ranges from 40-170 mm with a clitellum width of 3-5 mm (present on adults only), and 119-132 segments. The first dorsal pore appears on segment 12 or 13. The clitellum is from segment 14-16. When alive, the worm is a greenish brown or greenish grey in color. However, specimens that are preserved present with a dark green color on the posterior and a light green coloring on the anterior side (Chang et al., 2009).
A. hupeiensis is typically characterized as having a strong odor similar to “carrots freshly dug” and skunky chocolate giving it the nickname “stink worm.” This odor is found in coelomic fluid which is emitted from the dorsal pores upon irritation of the worm (Zaborski and Gittenger, 2001).
