The false potato beetle feeds on solanaceous weeds such as horsenettle, Solanum carolinense.

It also feeds on other solanaceous plants, such as species of ground cherry or husk tomato, Physalis spp., and bittersweet, Solanum dulcamara, but no growth and reproduction occurs when feeding on the potato, Solanum tuberosum.

L. juncta can be easily confused with its congener the Colorado potato beetle, Leptinotarsa decemlineata.

The eggs are slightly larger and fewer are found in a cluster.

The hump-backed larva is similar, but with only one row of dark spots on each side.