Afton State Park phenology, Sept. 2 through 8

Fall flowers, migration, and insects — and an update on park access.




4 minute read

Afton State Park (Greg Seitz/St. Croix 360)
Afton State Park (Greg Seitz/St. Croix 360)

From Afton State Park naturalist Linda Radimecky:

The big bluestem and Indian grasses are beautiful now and if you get to the park while the dew is still sitting you can see a myriad of spider webs hung between the grasses. If you look carefully you might see the garden spider that makes these beautiful orbs.

Another (human) event happening in September at the park is the bridge on the main park road is being replaced. The main road leading to the parking lots will be closed past the office starting on Monday, September 12, and is expected to reopen on Monday, September 26. There will be no camping or lodging reservations available during the bridge construction project. The visitor center, located near the parking lots, will be closed curing construction. The paved trail that runs alongside the road will be closed past the park office.

There are several places nearby to see the phenology events during this time including:  Carpenter Nature Center, St Croix Bluffs Regional Park, Cottage Grove Ravine Regional Park, Gateway State Trail, Brown’s Creek State Trail and Wm. O’Brien State Park.


On Wednesday the 7th, look for the planet Saturn to the left of the Moon. On the 8th Saturn will be to the right of the Moon.


Some American robins have begun to form flocks and slowly move south. Others will stay in this area all winter. Robins that go south just go far enough to find enough insects to eat to sustain themselves. Robins that stay in this area switch from eating insects to eating fruit. Look for groups of turkey vultures soaring overhead; they may have started on their way south also.


Gray squirrels are busy gathering black walnut seed pods, fruit, and acorns. Whitetail deer are growing in their gray winter coats, which will replace the summer red. And raccoons are on the prowl at dawn and dusk. Their closest relative other than the ringtails of the southwest is . . . the bear!

Amphibians and reptiles

Snapping and painted turtle eggs are hatching and young turtles moving from nests to the water. Young turtles are vulnerable to predators at this time. And turtles of all ages and also snakes bask in the September sunshine.


Monarch Butterflies have begun their southward migration, and the ones that survive all the hazards along the way will fly all the way to the oyamel pine forests of Mexico. On cool mornings look for groups of them clustered together on trees where they roosted overnight, and in the daytime watch for individual butterflies flying south. Green Darner Dragonflies migrate, also. In the late afternoon and evening look up to see them circling and slowly moving south.

There are over 350,000 species of beetles that have been identified, with more being found almost every day! You can tell beetles apart from other insects because the front pair of wings is hardened into what is called a “wing-case” protecting the second pair of wings, which the beetle uses for flying. One beetle common at Afton is the Goldenrod Soldier Beetle. As you can see in the photos, they visit many kinds of plants, not just goldenrod! There are approximately 3,500 species of soldier beetles in the world. The weevils are another group of beetles, and there are more than 60,000 species of them! One kind you might see at Afton is the pale green weevil, which is indeed pale green in color.


Wildflower season is winding down; in early September look for vervains and goldenrods on the prairie, and you may still see some jewelweed in wet areas. And sumacs are starting to turn read, signaling the coming of autumn.

Weather observations

Here are some weather observations for this week from past years:

Friday, September 22000: record rainfall of 1.97”
Saturday, September 32012: high in the low 80s
Sunday, September 42013: muggy and near 90°
Monday, September 52014: high in mid-60s
Tuesday, September 62015: thunderstorm, 5/8” rain
Wednesday, September 72016: humid with a high in the upper 70s
Thursday, September 82010: high 40s overnight

Photo/Image credits:

All photos copyright Nina Manzi, except:

  • Keith Henjum: Raccoon
  • Dean Lokken: American Robin, third Goldenrod Soldier Beetle, Turkey Vulture


You may republish this article online or in print under our Creative Commons license. You may not edit or shorten the text, you must attribute the article to St. Croix 360 and you must include the author’s name in your republication.

If you have any questions, please email

Afton State Park phenology, Sept. 2 through 8