This is probably an adult female leaf-footed bug (Acanthocephala declivis) — this species is named for the exaggerated “femurs” on its back legs, and the femurs are larger in the male, with impressive spikes. She’s about an inch and a half long, not including her antennae.
Leaf-footed bugs are named after the “leafy” extensions of their hind feet and legs, and are related to the similarly-shaped stinkbug. They come with an impressive pokey bit at the front (piercing/sucking mouthparts), which can be more than half the length of the insect’s body. This is normally used to penetrate the plants whose juices they eat, but can also be used for defense (ow). They do have wings and are good fliers. The wings overlap across the back with a characteristic teardrop-shaped “shield” which can have some nifty patterning.
This page on bugguide has an excellent key which can be used to tell species of Acanthocephala apart. I thought this was a Florida leaf-footed bug (Acanthocephala femorata), until I got hold of this key and realized that, based on the little tubercles on the pronotum (shiny black dots on its “shoulders” just above its head) and the distinctive shape of the tibial flanges (oh god I am getting so weird about insects), this is in fact A. declivis. Still a beautiful female, though.
Eggs are laid in spring, end-to-end in little strands. Adults overwinter in groups called aggregations. After the first hatching in the spring, all life stages can be found together.
They aren’t usually a problem in gardens, but they can damage plants (they eat sap, flowers, cones, fruit, and seeds) and are sometimes considered pests. They also occasionally move into homes as the weather gets colder, looking for a warm place to spend the winter.
The Austin Bug Collection has a great page on the Coreidae, and the University of California has a page on the related genus, Leptoglossus.