Research Summary
Roadside Surveys
- The majority of the milkweed (asperula) was found in the Edward's Plateau and Cross-timbers.
- The lowest number of milkweed was in the South Texas Plains.
- We are evaluating the relationship between abundance and precipitation.
Site-Specific Surveys
- Compared to roadside locations, there is more milkweed in the site specific locations.
Seed Viability and Germination
- Viability is not an issue.
- Germination is not an issue for most milkweed species.
- Most milkweed species have the photosynthetic characteristics of heliophytes.
Light Level Responses
- Significant differences in transpiration rates were at the highest and lowest light intensities tested.
- Significant differences in stomatal conductance were at the highest and lowest light intensities tested.
Patch Size
- There is not an optimum spacing or density of milkweed for monarch reproductive success.
Nectar Density
- Only under extremely high densities of nectar plants do you see increases in monarch success.
- Tropical milkweed will increase monarch success in the spring.
Best Management Practices
- Disturbance seems to increase the number of milkweed stems, but the effect is short-term.
Fire Ant Mounds
- All larval stages of monarchs are preyed upon by red imported fire ants.