Spider!

This female Black and Yellow Garden Spider has woven its web on our back porch screen.

The Argiope aurantia is also known as the Writing Spider or Corn Spider and is common throughout the lower 48 states.

Here’s what Wikipedia says:

The web of the yellow garden spider is distinctive: a circular shape up to 2 feet (60 cm) in diameter, with a dense zigzag of silk, known as a stabilimentum, in the center. The purpose of the stabilimentum is disputed. It is possible that it acts as camouflage for the spider lurking in the web's center, but it may also attract insect prey, or even warn birds of the presence of the otherwise difficult-to-see web. Only those spiders that are active during the day construct stabilimenta in their webs.

To construct the web, several radial lines are stretched among four or five anchor points that can be more than three feet apart. The radial lines meet at a central point. The spider makes a frame with several more radial lines and then fills the center with a spiral of silk, leaving a 5/16 to 3/8 inches (8 to 9.5 mm) gap between the spiral rings, starting with the innermost ring and moving outward in a clockwise motion. To ensure that the web is taut, the spider bends the radial lines slightly together while applying the silk spiral. The female's web is substantially larger than the male's, who builds a small zig-zag web nearby. The spider occupies the center of the web, usually hanging head-down, waiting for prey to become ensnared in the web. If disturbed by a possible predator, she may drop from the web and hide on the ground nearby. The web normally remains in one location for the entire summer, but spiders can change locations usually early in the season, perhaps to find better protection or better hunting.