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Insect and spider abundance

Maggie Furtner, Erin Wiemels, John Sherers, and Josh Hanselman
Ecology class, BIO 342, Biology Department, DePauw University
Fall semester 2016

Introduction
The goal of our research project was to compare the abundance of insects and the distribution of spider webs along the Rail Trail in the DePauw Nature Park.  The trail is heavily populated by insects and orb-weaving spiders, including Micrathena mitrata and Micrathena gracilis.  In September 2016, we observed an uneven distribution of spider webs on the two sides of the Rail Trail.  Spider webs were more abundant on the east side of the trail next to a patch of flooded forest and were less abundant on the west side of the trail. 

Hypothesis
We hypothesized that the uneven distribution of spider webs along the Rail Trail was due to a higher abundance of insects in the flooded forest on the east side of the trail.

Methods
We counted the number of spider webs on both sides of the trail for 4 weeks.  We installed 9 insect traps (18 traps total) on each side of the trail; 5 traps were unbaited fly paper and 4 traps were plexiglass plates covered with a sticky glue (Tree Tanglefoot).  We counted the number of trapped insects by size class (small, medium, and large).  

Results
There were significantly more spider webs on the east side than the west side of the Rail Trail.  Medium and large insects were significantly more abundant on the east side than the west side of the Rail Trail.  There was no difference in the abundance of small insects between the two sides of the trail. 

Discussion
Both spiders and insects were more abundant on the east side of the Rail Trail near the flooded forest.  Our results suggest that the flooded forest provides breeding habitat for insects, thus contributing to the uneven distribution of spiders and insects.