Centennial Waterfront Park, Idaho is host to many milkweed plants that host monarch butterfly larva.
The snake river is running thru the bottom of the canyon and hosts a number of water sports for recreation. Covered picnic areas make the park comfortable for an entire day in the park.
The perrine bridge is an icon of the the town of Twin Falls. Milkweed has found its place in the canyon below.
Milkweed is becoming more common in the park and on my visit in June 2015 I observed hundreds of healthy showy milkweed plants.
Commonly found on milkweed plants are monarch eggs and monarch caterpillars. I found one asclepias plant that was hosting a monarch egg on the underside of the leaf. It looks like the egg will be hatching a caterpillar in one or two days.
The milkweed appears to be very healthy. Despite the need to maintain the lawn areas for visitors the milkweed is treated very well. Park staff appears to have taken action to control the thistle plants by using localized spray, perhaps glyphosate. I was very pleased to see that the milkweed was not targeted by the spray and appears to have been actively avoided.
The milkweed is in full bloom in mid June. Blooms will begin to wilt thru July and the amazing seed pods will form in their place. June and July are great months to smell the fragerent milkweed blooms.
If you visit in July or August you are likely to see leaves on the milkweed that are chewed on by caterpillars. The monarch caterpillars feed on the leaves. When fully grown caterpillars reach instar 5 they begin the metamorphosis into butterflies by forming a chrysalis.
You may find a chrysalis on the milkweed plant. It's not uncommon for the caterpillar to crawl away from the milkweed plant and be hanging from a park bench, railing, branch or other object in the nearby area. It's uncommon for the chrysalis to be found much more than twenty feet from a milkweed plant.
A butterfly that is commonly confused with the monarch is the Viceroy butterfly. The viceroy has similar orange and black color to the monarch.
The host plant of the viceroy is not milkweed. The black line on the wing does not appear on a monarch. In flight I thought this viceroy was a monarch. When it landed I was able to identify it as the viceroy that it clearly is.