The Monarch Monitoring Project is a long-term study on monarch migration through Cape May, NJ. It is a part of the New Jersey Audubon Research Department, and closely affiliated with the Cape May Bird Observatory.

Friday, October 5, 2018


Finally, we have had some impressive monarch days in Cape May! This week we have had census numbers exceeding the rest of the season by large margins, with Friday morning's census being our highest yet: 105 monarchs in 20 minutes. The seaside goldenrod has begun to bloom as well, a favorite nectar source for our fall migrants. Keep a look out for monarchs nectaring on the dunes across the point in the weeks to come! 

With this increase in butterflies, we also have more visitors attending our weekend tagging demonstrations (2:00 at the State Park, Friday to Sunday through Oct. 14) One of the things we will always suggest to help monarch populations at these demos is to plant milkweed anywhere and everywhere. Since milkweed is the only plant a monarch caterpillar can eat, they are absolutely necessary for monarch butterflies. Because of this, milkweed has become synonymous with monarchs.

Milkweed is also a host plant for a wide variety of other insects. Planting a milkweed patch creates an entire community of organisms that both depend on the milkweed and each other for survival. If you have a patch of milkweed at home, keep a lookout for these other milkweed dependent bugs, and you can start to look at the milkweed patch not only as food for monarchs, but as a village with many different residents!

Large milkweed bug

  • They do not eat the leaves of the milkweed plant, but use the seeds as their food source
  • Certain populations of large milkweed bugs are migratory, while others are not
  • Like the monarch, the large milkweed bug is toxic to predators

Milkweed leaf beetle

  • While milkweed is a major host plant for these beetles, they also will use some other plants in the larger milkweed family

  • Milkweed aphids

    • Aphids, in small colonies, are very unlikely to cause significant harm on your milkweed plant
    • Unlike most other insects, they give birth to live young
    • Female aphids are able to reproduce without a male, and if needed, one could create hundreds of clones of herself

    Milkweed tussock moth

    • Another milkweed caterpillar, the milkweed tussock moth gains its toxicity to predators from the host plant and retains it to adulthood
    • Like the viceroy butterfly, these caterpillars are a Mullerian mimic of monarch caterpillars

    [Post by Field Naturalist Sarah Crosby]

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