Milkweed Bugs...

 ...will feed on young leaves, flowers and developing pods, but their preference is for the milkweed seeds inside the pods, so you'll frequently find large congregations clustered together on the outside of the pods. They have the ability to inject digestive enzymes into the plant tissue and then suck the liquified plant material out through their beak. Because of the length of their mouthparts they're only able to feed on the outside layers of seeds in each pod, leaving many interior seeds intact for plant reproduction. The females can deposit up to 30 eggs per day for about a month, and in mild climates they can produce up to 3 generations per year, but here in Wisconsin just a single generation is produced, as they can't tolerate the cold. The milkweed bugs (like many of their human counterparts) travel south to warmer climates for the winter. As their coloring suggests, they're poisonous to predators due to cardiac glycosides in the milkweed they eat. At the very least, eating a bunch of bad-tasting MB's will cause a predator to vomit and to develop a strong aversion to eating them next time it spots them. 
Thanks to JDO for hosting TinyTuesdays this month.   :)