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We investigated abundance and web characteristics (web elevation and spiral area) of the spiny orb weavers Micrathena gracilis (Walckenaer 1805) and Micrathena mitrata (Hentz 1850) using transect surveys in oak-hickory forest stands in west-central Illinois. Surveys resulted in 153 collected individuals or observations of adult females (70 M. gracilis and 83 M. mitrata). Peak abundance of both species occurred in late July, with a density of 0.03 females per m2 for each species. Web spiral area and web elevation were both greater for M. gracilis than M. mitrata. Micrathena mitrata web spiral area was larger in plots in which spiders had been previously removed than in plots without removal. These results suggest that the two species have different vegetation structure or microclimate preferences, and may respond to availability of unoccupied habitat differently. [ABSTRACT FROM AUTHOR]

The article presents information on an activity that involves observing spiders. Almost all species of spiders are venomous but only 20 of them are dangerous to people. The brown recluse and the female black widow spiders are the two dangerous spiders found in the United States. While studying a spider, students should try to be as unobtrusive as possible otherwise the spider will move to some more private location. Spiders usually bite only to prevent intrusion of an outsider in their territory. Some of the activities in the study of spiders include describing and estimating the length of the legs and number of joints in the legs, making inferences about the quality of spider's vision according to its behavior and determining whether a spider hunts or captures prey through web. Observations of students should include at least one three-dimensional drawing of their spiders highlighting the two body parts Cephalothorax and abdomen.