Both and butterfly milkweed opened their flowers this week, marking the start of peak nectar season on the Front Range. These plants are critical refueling stops for monarchs in migration, and their reliable bloom timing anchors the pulse of the entire prairie ecosystem through early summer.
have been active along the corridor — four sightings in the past two months confirm the broader butterfly migration is in motion. The landscape is waking up.
Water quality remains a shadow over this seasonal renewal. Ralston Creek below continues to carry a pollution burden that triggered federal impairment designation; its cleanup plan remains pending, with no timeline set. For now, the flowering and the insects are thriving — but the stream that once powered this grassland sits on hold.
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Not everything in this landscape is native. Broad-leaved sweet pea, an invasive plant, is spreading through disturbed areas near the trail edges, and musk thistle, also invasive, has pushed into the open ground between native forbs. Both compete for the dry, open habitat that butterfly milkweed depends on. Neither is a host for the hairstreak. The more these invasive plants establish in rocky, sunny patches, the less suitable ground remains for the milkweed and the butterfly tied to it.
The orange of the butterfly milkweed flowers is distinct from almost everything else blooming at this elevation right now. Stand near a plant and give it a few minutes. The hairstreak moves quickly but lands with deliberate stillness, wings folded, green against green.
The bergamot stands here also carry other visitors worth noting. The golden northern bumble bee, which is a threatened species in this region, works the remaining open flowers with a focused persistence. The plains bee assassin, a native ambush predator, sometimes waits motionless on flower heads for exactly that kind of visitor. Both species are present in this area, and both are tied to the bergamot in different ways: one as a pollinator, one as a predator of pollinators. The goldfinch, arriving weeks later for the seeds, is using a resource the plant produced partly because those earlier visitors did their work.
The bergamot stems stand about waist high in full sun. If you are near a patch of them, look at the dried heads. Many will show small gaps where seeds have already been taken. Some stems will still be moving. The goldfinch's call is a bright, ascending note, often given in flight — four or five syllables that rise and then fall. In the heat of a peak summer afternoon, with the milkweed blooming and the bergamot going to seed, that call is one of the more reliable sounds in this landscape.
The bergamot stands here also carry other visitors worth noting. The golden northern bumble bee, which is a threatened species in this region, works the remaining open flowers with a focused persistence. The plains bee assassin, a native ambush predator, sometimes waits motionless on flower heads for exactly that kind of visitor. Both species are present in this area, and both are tied to the bergamot in different ways: one as a pollinator, one as a predator of pollinators. The goldfinch, arriving weeks later for the seeds, is using a resource the plant produced partly because those earlier visitors did their work.
The bergamot stems stand about waist high in full sun. If you are near a patch of them, look at the dried heads. Many will show small gaps where seeds have already been taken. Some stems will still be moving. The goldfinch's call is a bright, ascending note, often given in flight — four or five syllables that rise and then fall. In the heat of a peak summer afternoon, with the milkweed blooming and the bergamot going to seed, that call is one of the more reliable sounds in this landscape.
