It's that time of year when pipevine swallowtail butterflies are flitting about the American River Parkway, dodging bicyclists drawn by the great weather.
In spring, the greenish-black, orange-spotted butterflies lay their eggs on the leaves of the Dutchman's pipe vine. After the eggs hatch later in the spring, the caterpillar larvae eat the leaves of the vine.
It is up to the bicyclists to dodge the caterpillars as they wiggle across the bike trail black top in their travels from vine-to-vine.
The National Weather Service expects the spring weather to be mild - around 70 degrees all week. A slight chance of rain is forecast for Wednesday when clouds move into the Sacramento region.
Otherwise, it will be perfect flying and biking weather on the bike trail.
Call The Bee's Bill Lindelof, (916) 321-1079. Follow him on Twitter @Lindelofnews.