Monarch Watch Blog

Monarch Population Status

Wednesday, September 14th, 2016 at 8:24 pm by Jim
Filed under Monarch Population Status | 14 Comments »

It was apparent as early as late May that the migration, and the subsequent overwintering population, was going to be much lower this year than in 2015-2016. The projections outlined in the Blog post of 7 July have largely come true. The one surprise has been the production of late season monarchs in Kansas, Missouri and North Carolina. There have been reports from each state describing sites with large numbers of monarch larvae defoliating patches of naturally occurring milkweeds and in some cases milkweeds in gardens. The numbers of larvae reported by observers in these areas exceed anything reported this season further to the north, where most monarchs are typically produced.

The timing of this production, along with summer observations of low numbers of adult and larval monarchs in these states, suggest a southward movement of reproductive monarchs in late July and early August – a possible manifestation of the little-understood late summer movement southward of monarchs that I’ve dubbed the “pre-migration migration”. How much this more southerly monarch production will contribute to the migration and the overwintering numbers remains to be seen. That said, it still seems likely that the area of trees occupied by monarchs in Mexico this winter will be similar to that measured in 2014 (1.13 hectares).

  1. 14 Responses to “Monarch Population Status”

  2. By Jane smith on Sep 14, 2016

    That explains the dozen Monarch larvae I observed in Landen, Ohio!

  3. By Abbey Harkrader on Sep 15, 2016

    Northern Iowa also has a very late production. I didn’t find any larvae or adults in July like I normally do and was getting very concerned until the adults and eggs started showing up in August. Once they got here they reproduced like crazy. I don’t think I saw full defoliation, but they are everywhere. I released 10 adults the last couple days that I reared and I saw 2 larvae just yesterday, the latest I have ever noticed. The adults are flying everywhere but I haven’t seen any gathering together.

  4. By Brenda Leonard on Sep 18, 2016

    We’ve seen one and only Monarch in our yard and area Sept 17, Midlothian VA
    We have lots of milkweed but he didn’t tarry.

  5. By Jean Marie Hagerman on Sep 20, 2016

    We have been seeing something similar here in southeastern PA. Several of us who are rearing monarchs in the Hanover (17331) and Spring Grove (17362) areas are finding numbers of caterpillars every time we go out in the fields to get more milkweed for feeding. At one roadside area about 1/16 of a mile in length we found 65 eggs and caterpillars on 9/19. Since then we have continued to find some every 2 to 3 days, although the numbers have continued to diminish. Others have reported the same type situations where they get their milkweed.

  6. By Kevan Prati on Sep 24, 2016

    Here, near Dallas, TX, I purchased milkweed plants in April 2015 from a local master gardeners’ spring show for my flower garden intending to make it more monarch-friendly. I have a good number of nectar rich plants but saw no monarchs in 2015.
    This year, the milkweed plants cover a 12′ by 12′ area of the flower garden and some are over 6 feet tall! About a month ago I noticed a first time visitor, a queen butterfly. Yesterday, Sept. 23rd I saw my first monarch and she was laying eggs on the plants. Today, the 24th, I still have a monarch – don’t know if it is the same one – laying eggs. Our average first freeze date isn’t until Nov. 10th so the caterpillars will have plenty of time to grow and complete metamorphosis. I would gladly post a picture of the milkweed patch in the garden but don’t know how to do that on this blog.

  7. By Tina Roeda on Sep 25, 2016

    I live in the Winston-Salem area of NC, and last Saturday was the first female Monarch we had seen all summer. She stayed by us for 4 days laying eggs. I brought in 11 of the eggs, and now have caterpillars inside my screen porch and more hatching outside. I am hoping we do not get a frost before they are ready to head south. Last year we had caterpillars mid August, so they were about a month later this year.
    I also found 15 Black Swallowtail caterpillars today on 1 fennel plant…Have to go find more food for them to eat.

  8. By Eric on Sep 29, 2016

    This year, in Annapolis, MD, we have had record numbers of monarchs visiting our patch of milkweed laying eggs and the most caterpillars (around 40) we have seen on our milkweed. In fact the milkweed looks pretty used up. Usually we get maybe five to ten caterpillars on the plants. Hopefully this is a predictor of good counts for the upcoming winter census in mexico.

  9. By russ elliott on Sep 29, 2016

    Seeing hundreds of monarchs, swallowtails and other species here @ the end of Sept ’16 crossing over Blue Ridge Parkway south of Asheville, NC–Wondrous!!

  10. By CAROL FITZPATRICK on Oct 6, 2016

    My house sits on a 2 & 1/2 acre lot. 1.13 hectares is about the size of my lot. This is terrible news. The entire population of future monarchs rests on them surviving the winter in trees that sit on property the same size of my little lot? Incredible and to me it spells dooms day for our wonderful monarchs. Their forest should have been made a Mexican National Treasure long ago. I don’t understand how there’s no outrage. MONARCH LIVES MATTER!!

  11. By Patricia Bartlett on Oct 16, 2016

    Since I did not see caterpillars this year, but did a few Monarchs, I have lots of Milkweed wild, I wonder if I should plant Milkweed as well. Do you think that this would help. This is North Carolina mountains but right at Tennessee/NC and Virginia border so quite cooler than the rest of the NC Mountain area.

  12. By Christy on Oct 17, 2016

    I observed 10-20 monarch cats on two separate patches of milkweed in my yard in Durham, NC about 12 days ago (around 10/5). There were two visible chrysalis on nearly-stripped milkweed plants that formed six or so days ago. One disappeared, the other is still there. There were also some cats crawling off toward a very large gardenia in my garden, so I have hopes that there may be some chrysalis elsewhere. I am considering moving the the chrysalis that is visible inside so that it can avoid the fate of the other one, but am conflicted because I really don’t know what I’m doing and am worried about doing more harm than good. In any case, this has all happened later in the season than I expected.

  13. By Bibi Estlund on Oct 18, 2016

    These observations definitely coincide with my own sightings this year. It will be very interesting to see what the “pre migration migration” means for overwintering populations. Thank you for this valuable information!

  14. By April Heim on Oct 29, 2016

    I monitored three locations in Kansas City, Missouri. In two of them the milkweed was stripped clean by huge numbers of larva. The other had about 15 larva.

  15. By B Whalen on Oct 29, 2016

    I saw two Monarchs today (October 29). I confirmed they were not VIceroy. I live on a farm in the panhandle of Montgomery County Illinois. This year I put 1.3 acres into a wildflower meadow. Next year I am adding Milkweed.

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