Welfare of Monarch Butterfly Larvae During Drought

Monarch caterpillars face welfare challenges during drought events as milkweed quality declines and plants produce more defensive chemicals in response to stress.

Key Facts

Stressed milkweed plants produce higher concentrations of cardenolides as defense
Monarch caterpillars can tolerate cardenolides but high concentrations reduce survival
Drought stress reduces milkweed nutritional quality affecting caterpillar growth
Climate change is increasing drought frequency in monarch breeding range
Milkweed availability during drought is reduced through plant death and dormancy

Welfare Considerations

Monarch caterpillars on drought-stressed milkweed may experience nutritional deficiency affecting development and survival. High cardenolide concentrations from stressed plants are toxic at sufficient levels. Reduced plant biomass means caterpillars must travel farther to find adequate food, burning energy reserves. These welfare challenges occur at the individual level and aggregate across millions of caterpillars during drought events. Maintaining milkweed diversity including less stressed plants helps buffer these welfare effects.

What You Can Do

Plant diverse milkweed species including some in sheltered positions less affected by drought
Provide water near milkweed plantings during drought to maintain plant condition
Support climate action that reduces drought frequency in monarch breeding range
Participate in citizen science monarch monitoring programs that track welfare outcomes