Kingsville, Mo. ? Ecologists in Kansas and Missouri say extreme temperatures are killing a large number of butterflies and could hurt their southern migration next month.

Millions of monarch butterflies are expected to migrate south through the two states in less than a month in their seasonal trip from Canada to Mexico.

KSHB-TV reported that the Powell Botanical Gardens’ annual butterfly festival east of Kansas City is seeing the lowest number of monarchs in a decade.

Kansas University Monarch Watch director Chip Taylor says flowers that should bloom in the fall already are finished blooming, which could be a problem for butterflies that need the plants’ nectar for their journey.

Horticulturists say fewer butterflies also could mean fewer birds, bees and flowers as the drought continues.