Species Council

Invasive of the Day...

To highlight 2011 National Invasive Species Awareness Week, DISC highlighted the following 'Invasives of the Day'.

Friday, March 4th

Nutria (Myocastor coypu)

Nutria (Myocastor coypu) are large semi-aquatic rodents native to South America.  They were introduced in the United Sates for fur farming.  After nutria farming collapsed in the 1940s, thousands were released into the wild or introduced as a natural weed controller.  They have been found in 22 States.

These large rodents can weigh up to 20 lbs., but on average weigh between 12-15 lbs. They are brown in color and are commonly mistaken for muskrat or beaver.  Nutria are easily identifiable by their large yellow-orange front teeth, rat-like tail, and white whiskers.  Nutria are highly prolific and breed all year. They can have up to three litters per year with litters averaging four to five young. Young are born fully furred and active, and can survive away from their mother after 5 days of life.

   

Feeding directly on the root mat of marsh vegetation, nutria have left many areas with holes and deep swim canals.  Areas devoid of vegetation are called "eat outs" and the swim channels are called "runs."  The negative impact this invasive species has on native vegetation and associated wetlands is critically important.  Nutria excavate and feed on the roots of marsh grasses, leaving areas devoid of vegetation called “eat outs”.  Without plant roots to stabilize the soil, water moves in and washes exposed soil away, quickly eroding marshes and converting them to open water.  Nutria also fragment marshes by creating swim channels.  These channels permit the movement of saltwater into isolated, interior ponds that support submerged aquatic vegetation. The increase in salinity and turbidity limits the growth of submerged aquatic vegetation, important for making dissolved oxygen and serving as food and shelter for many native species. As more marsh plants are removed, damage to wetlands from sea level rise, land subsidence, tidal flooding and salt water increases because there are fewer plants to act as a buffer against erosion. 

Thank you Steven Kendrot, Chesapeake Bay Nutria Project, for submitting this invasive of the day. 

 

 

 

Thursday, March 3rd 

 

Brown Marmarated Stinkbug (Halyomorpha halys)

The Brown Marmorated Stinkbug is a pest insect native to Japan, China, Korea and Taiwan.  They were accidently introduced in North America probably as stowaways on packing crates from Asia.  Some records show they were first collected in Allentown, PA in 1996, but were probably here earlier than that.

Having a diverse palette, these pests are polyphagous (eat many things) and have an assortment of host plants in which they feed.  In Asia, they attack shade and fruit trees and various vegetable and leguminous crops, like soybeans.  In North America, that list has expanded to include species such as Catalpa spp., Lonicera spp., and Acer platanoides.

When stinkbugs are disturbed or crushed, they omit a ‘stinky’ odor from glands under their wings.  The smell becomes more apparent when multiple stink bugs have been disturbed.

Stinkbugs pose no threat to humans, but they are a nuisance when they enter homes.  They are more of a problem to farmers because of the damage they can cause to crops.  To prevent stinkbugs from entering your house, seal cracks around windows, doors, siding, utility pipes, and other openings with caulk.  Applying pesticides in the fall just before the bugs start to invade houses can be done, but is not highly recommended because most pesticides break down in sunlight, therefore decreasing the effectiveness of the pesticide.

Thank you Delaware State Parks, Environmental Stewardship Program for submitting this invasive of the day.

 Photo credit: www.bugwood.org

Wednesday, March 2nd 

Japanese Stilt-grass (Microstegium vimineum)

Japanese stilt-grass is an annual grass with a sprawling habit that cnan grow to 3 feet in height.  Its thin, pale green, lance-shaped leaves alternate along the branched stalk and have an asymmetrical silvery stripe of reflective hairs down the middle of the upper leaf surface.  Delicate spikes of flowers emerge from slender tips beginning in late summer and continue into fall.  Seeds can persist through the fall. 

Stilt-grass commonly occurs on stream banks, flood plains, wetlands, moist forests, uplands, roadsides, and home lawns.  It is most common in shaded areas where there has been some sort of soil disturbance such as mowed or tilled fields and trail edges.

Japanese stilt grass was introduced  to Tennessee in the early 1900's.  It was used as packing material for delicate items and probably escaped as a result.  Stilt-grass is adapted to low light conditions and threatens native understory vegetation in open to shady locations. It spreads opportunistically following disturbance to form dense patches, displacing native vegetation as the patch expands.  Japanese stilt-grass is a colonial species that spreads by rooting at nodes along the stem.  A new plant emerges from each node.  It also spreads by seed and each plantcan produce an estimated 100-1,000 seeds.  Once established at a site, seed stored in the soil will ensure re-rowth for several years.  Studies have shown that stilt-grass seed remains viable in the soil for at least three years. 

 Thank you Delaware State Parks, Environmental Stewardship Program for submitting this invasive of the day.

 

Tuesday, March 1st: 

White Nose Syndrome (Geomyces destructans)

We don’t typically think of funguses as being invasive but there is a new fungus in town that may have originated in Europe (at least it is new to the U.S. and has been documented in Europe). It is aptly named Geomyces destructans and it is a major player in a disease that has killed over a million bats so far and is steam rolling its way through north America. White-Nose Syndrome (WNS) is named for the white fungus that grows on the muzzles, tails and  wing membranes of many affected hibernating bats.  G. destructans is the only fungus known to grow on living tissue and recent research has shown that it interfers with physiological functions during hibernation. Bats affected by WNS can have low body weight and awake during hibernation more often than normal.

Although there is still some debate among biologists, the fungus appears to be the cause of WNS and bats are dying in unprecedented numbers in and around caves and mines from Canada to North Carolina to Misourri. In some hibernacula, 90 to 100 percent of the bats have perished.

In Delaware, the fungus was found on the skin of bats that had recently arrived at their summer roost sites in April 2010. Once the bats leave their caves, they typically groom the external fungus off their fur, but part of the fungus can persist in the bats’ tissue for longer periods of time. Since the fungus does best and only appears to grow in cold, damp places like caves, it’s not likely to survive the hot Delaware summer. However, very little is known about summer persistence of the fungus and its life cycle is still being investigated. Delaware Fish & Wildlife’s Bat Program is monitoring the state’s bats for the effects of White-nose Syndrome with a variety of research projects and with the help of volunteer “Bat Spotters.” If you’re interested in learning more or joining the Bat Spotters, ‘like’ the Delaware Bat Program on facebook, click www.fw.delaware.gov/bats, or call Erin at 302-735-8669.

 Thank you Holly Niederriter and Erin Adams, DE Division of Fish and Wildlife, for submitting this invasive of the day 

  Monday, February 28, 2011- Parrot-feather (Myriophyllum aquaticum) 

This aquatic plant is a member of the milfoil family, whose underwater leaves have the appearance of a feather.  Parrot-feather is notable in that the top of the plant has grey-green feather shaped leaves that stand above the water.  It can actually grow entirely out of the water on saturated soil and has been found along the old swimming area at Becks Pond.

Its presence in Delaware is most likely due to the popularity of ornamental water gardens as it is often sold as an ornamental species.  Unlike some other ornamentals, parrot-feather can over-winter in Delaware waters.  Unfortunately, it also grows very quickly and even a broken-off stem can be the source of a new population.  Many private pond owners, who received some free plants from well-meaning friends, have found that it can quickly take over their ponds.   It has been increasingly found in public waterways in Delaware from the upper Nanticoke Branch in Greenwood to a roadside ditch near Blackbird State Forest.  Control is difficult due to its waxy coating on the part of the plant that grows above the water.  It is important that excess plants be disposed of by freezing or drying and not be composted or released into other waters. 

 Thank you Cathy Martin & Jared Jacobini, DE Division of Fish and Wildlife, for submitting this invasive of the day.