Each fall, Hidden Oaks Nature Center hosts families for a monarch tagging and native pollinator garden program. It’s part of the citizen science project Monarch Watch (https://monarchwatch.org.) If we lived in Kansas, where Monarch Watch is based, we would have the opportunity to potentially tag thousands of monarchs during their peak migration week. In Annandale, Virginia, we may tag 50 over the season.
Monarchs tend to hug the coast as they wing their way towards Mexico. The biggest concentrations for tagging are areas such as Cape May in New Jersey, Point Lookout State Park in Maryland, and the Eastern Shore of Virginia National Wildlife Refuge. In Northern Virginia, Green Spring Gardens in Alexandria attracts monarchs with their nectar and host plants. We are having significantly better success this year at Hidden Oaks with monarch eggs being laid on our milkweed patches. The monarchs we tag in our September programs are ones that we rear from first instar caterpillars purchased through Monarch Watch. The most we have ever had to tag in one program was six, so dreams of netting one monarch after another for a tag and release is just not likely in this area.
Surprisingly, several homeowners’ gardens seem to attract a high number of monarchs each season. Usually a combination of large areas of preferred nectar plants, such as asters and goldenrod, will lure monarchs into the patches of milkweed. Since each caterpillar needs about 18 inches of plant material to grow and a monarch can lay over 200 eggs, a large patch of milkweed is helpful in establishing a backyard experience in the wonder of metamorphosis. The reasons as to why one well-established garden succeeds in attracting monarchs while another does not is a mystery.
Monarch numbers in the metro D.C. area are not significant until mid to late summer. The few monarchs that do arrive in spring struggle to find enough monarch plant material to develop effectively. Planting common milkweed, which is a tall, broadleaf plant, is preferable for monarchs due to the amount of milkweed needed for the metamorphosis. Tidy, compact milkweeds with common names of swamp and butterfly weed are attractive. Unfortunately, their thinner leaves and shorter profile cannot support multiple monarch caterpillars.
Watering milkweeds in the summer enables them to thrive in late summer and early fall. The final breeding generation of monarchs arrive then and need fresh host plants on which to lay eggs. The last generation is the migrating generation. This late summer/early fall monarch is physiologically different from the previous four generations and will not be ready to mate until late February/early March. Ideally, they will be in Mexico at that time, arriving by early November. Heading to Florida is a poor option as a deadly bacterial infection is rampant in the monarch population.
To see a steady stream of monarchs, head to coastal areas that are common stopover spots and that have large areas of nectar plants. Sometimes streams of monarchs are seen out of high-rise office windows or gliding thousands of feet up in the sky on thermals that help them soar to Mexico. A few generations later we hope to see their descendants next summer.
According to Monarch Watch and based on our latitude, our area’s peak migration time is around September 25. Hidden Oaks Nature Center had a dozen or so monarchs in various stages of development they reared through mid-September 2020.
Author Suzanne Holland is the Visitor Services Manager at Hidden Oaks Nature Center.