July 31, 10 am.
Today we are working as a team to try and control some of the invasive thistles and other invasive plants that grow on the mitigation lands. we are looking for the thistle called Canada thistle or Creeping thistle, Circium arvense. Canada thistle is a native of southeastern Eurasia. It was introduced to Canada as a contaminant of crop seed as early as the 1600s. The rapid spread of Canada thistle led to control legislation as early as 1795 in Vermont and 1831 in New York. It is probably the most widespread of all thistle species. We find a large patch along Mill creek and begin to try pulling it out. it very hard to pull out of the ground for many reasons, the ground is dry and compacted here and its leaves and stems are covered by hundreds of sharp, nasty prickles. The flowers are a lavender purple color and at first glance, seem like a pretty wildflower. We spend an hour or so cutting the flower heads off and bagging them in plastic bags. Each flower head can produce up to 5000 seeds so it is a good thing to cut these off and dispose of them. When I return to the office and look up information about this plant I discover it is a perennial thistle, living year after year and is woody at the base. This is another reason why it is more difficult to get rid of. This plant has extensive roots which makes it hard to get rid of it by digging it out, sometimes going down 6 to 8 feet and growing out from the plant 20 feet. This “creeping thistle” can then send up plants all along its 20 foot long horizontal root! We see evidence of this as we trace the young plants out from the parent plant. The day has turned hot but this work is very satisfying as we look over the area and don’t see a single flowering thistle. If we are able to do this for a few years perhaps this will decrease the population in the future.
As we are in the midst of this project, Chris Bartow, the project manager calls to me about a spider he has found in the mugwort plant near the thistles. I can see it is a beautiful, large garden spider, the Argiope aurantia. The bright yellow and black abdomen is a diagnostic characteristic of this spider. Yellow garden spiders are large, orb-weaving arachnids, meaning they spin a circular web. Most spiders have two claws on each foot, but orb weavers have an additional claw to help them spin their complex and gorgeous webs. The Argiope spider may be active both day and night, attacking insects that are trapped in its web. The photo shows one that has caught and begun to eat one of our numerous dragonflies. (This photo was taken by Jake Stubberfield, our assistant manager on the project) They often construct and repair their webs after dark, but may do this in day time and it may eat and respin its web each night. Once they find suitable sites for their webs, they will tend to stay a long time there unless the web is frequently disturbed, or it isn’t a good spot for food. They are not known to bite humans unless extremely provoked and the result is said to be only as bad as a bee sting. The males are smaller (as in many species of spiders) and don’t have as much yellow and black on their abdomens. They are often found on the edges of the web, or even in their own smaller web nearby. We look for a male, but only see another female Argiope in a nearby bush. In past years I have had a few of these wondrous large spiders in my garden and I enjoy watching them close up. The morning dew allows us to see their webs as the shining works of art they truly are.