Look for Milkweed Assassin Bugs on milkweed plants as well as flowers.
Details of the:
Milkweed Assassin Bug
Category: True Bug
Common name: Milkweed Assassin Bug
Scientific Name: Zelus longipes
Other Names: Long-legged Assassin Bug
Size (Adult, Length): 14mm to 20mm (0.55in to 0.79in)
Identifying Colors: red, black
Additional Descriptors: beneficial, painful, biting, fang, flying, predator
North American Reach (Though Not Limited To*): Alabama; Arkansas; Connecticut; Delaware; Florida; Georgia; Illinois; Indiana; Iowa; Kansas; Kentucky; Louisiana; Maine; Maryland; Massachusetts; Michigan; Minnesota; Mississippi; Missouri; Nebraska;New Hampshire; New Jersey; New York; North Carolina; North Dakota; Ohio; Oklahoma; Pennsylvania; Rhode Island; South Carolina; South Dakota; Tennessee; Texas; Vermont; Virginia; West Virginia; Wisconsin; British Columbia; New Brunswick; Newfoundland and Labrador; Nova Scotia; Ontario; Prince Edward Island; Quebec; Mexico
* Keep in mind that an insect's reach is not limited by lines on a map and therefore may appear in areas/regions/states beyond those listed above.