Arboretum: Orbweavers and Turning Leaves

I found a spider clinging to the underside of an American elm leaf yesterday. Thanks to John and Jane Balaban at BugGuide, I now know it as a marbled orbweaver (Araneus marmoreus).

Marbled orbweaver
Marbled orbweaver

According to Spiders of the Eastern United States, marbled orbweavers build vertical webs in woodlands, fairly low to the ground. They are active mainly at night, feeding on large flying insects such as cicadas, katydids, and beetles.

Marbled orbweaver
Marbled orbweaver

The coloration and pattern of this spider is somewhat variable. This spider had a mostly yellow abdomen with a red pattern and a reddish cephalothorax. Its legs were banded.

Like many spiders in this family, its legs had spines on them.

Marbled orbweaver

Below is a close-up of this spider’s face. It has eight eyes, but only six appear visible. The leftmost and rightmost eyes are actually two eyes very close together, which can be seen in these photos.

Face of marbled orbweaver
Face of marbled orbweaver

The past few nights have been chilly; fall is making itself known. One of the first trees to turn color in the Arboretum, a Schlesinger red maple, has already done so.

Schlesinger red maple
Schlesinger red maple

The Schlesinger maple was discovered by the first director of the Arboretum, Charles Sargent, in his neighbor’s yard. The cultivar Schlesingeri was named after the neighbor, Barthold Schlesinger.

The young maple pictured (accession 408-91*A) is a cutting from the original Arboretum accession across from the Visitor Center. That original tree is over 120 years old and reaching the end of its life.

More on the Schlesinger maple from Arnoldia magazine. (pdf)

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