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Insect Populations Decline In Number And Diversity

6-27-18 common milkweed IMG_7097Thirteen years ago I went and sat in a field full of Common Milkweed (Asclepias syriaca). The photographs I took of insects visiting the fragrant blossoms ended up being the subject of my first children’s book, Milkweed Visitors. The number and diversity of invertebrates in that patch of milkweed was astounding. Over a decade later I find milkweed flowers alarmingly free of insect visitors. I first noticed this several years ago, and unfortunately the trend has continued. An occasional honey bee or bumblebee, perhaps a swallowtail butterfly or a red milkweed beetle or two can be seen, but nowhere near the number or variety of insects that you found just a few years ago.

Recent studies show that insect populations are declining dramatically not only in milkweed patches, and not only in North America, but in many parts of the world. A global index for invertebrate abundance showed a 45 percent decline over the last four decades. (Yale School of Forestry and Environmental Studies). Researchers say various factors, from the rampant use of pesticides (in particular, neonicotinoids), the spread of monoculture crops such as corn and soybeans, urbanization, and habitat destruction contribute to this decline.

This phenomenon affects everything from pollination to the documented decline in bird populations that feed on flying insects. However, thus far, only the decline of honey bee populations has received widespread public attention, in large measure because of their vital role in pollinating food crops. The rest of the insect world has been widely ignored. Insects play a major role not only in pollination but as predators of insect pests and as food for birds, amphibians and bats. Who knows how many plant species live in symbiotic relationships with highly specialized insects.

Given the importance of insects for agriculture, biodiversity and the health of ecosystems, one hopes that studies regarding the decline of insects will increase in the near future.  We can all contribute to a greater understanding of what is happening by participating in “citizen science” projects which undertake monitoring of specific insect species. A list of such projects and how to get involved can be found at

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29 responses

  1. nelsondonnal

    Thank you for this important piece, Mary. It has also disturbed me that the focus has been so much on honey bees, while so many other insect species have declined. I see the same thing here in my garden of over 30 years observation.

    June 29, 2018 at 8:39 am

  2. When I was a child, the windshield of the family car had to be scrubbed free of thick coatings of bug residue. Frequently. No longer ever necessary.

    On Fri, Jun 29, 2018, 8:31 AM Naturally Curious with Mary Holland wrote:

    > Mary Holland posted: “Thirteen years ago I went and sat in a field full of > Common Milkweed (Asclepias syriaca). The photographs I took of insects > visiting the fragrant blossoms ended up being the subject of my first > children’s book, Milkweed Visitors. The number and diversity ” >

    June 29, 2018 at 8:49 am

  3. I have noticed this too Mary. I have lots of milkweed in my yard and 10 years ago, I had lots of milkweed bugs, monarchs and more, but today, very few. A very disturbing trend.

    June 29, 2018 at 9:10 am

  4. Marilyn

    That’s so interesting! I’ll follow up.on the link you provided. So often we miss the larger picture. Regarding pollination, I see many sorts of insects (and hummingbirds) in the flowers. Are honeybees the focus because of the honey? Monarch butterflies because they are spectacular?

    June 29, 2018 at 9:12 am

  5. Alice Pratt

    Your “Milkweed Visitors” book is awesome….the fragrance of Milkweeds is quite special! I have a sunny area in the yard with many Mikweeds & Goldenrods & St John’swort ‘Sunburst’…a shrub…..definitely a bee paradise, but haven’t seen many other insects.

    June 29, 2018 at 9:43 am

  6. I too have noticed the decline of insects on my milkweed in Western Maine. In 2012 I photographed 12 different insects in a day or two, but last summer I got almost none.

    June 29, 2018 at 9:47 am

  7. Peter Hope

    On Sunday, May 20 Krista Tippett had Michael McCarthy on her show “On Being”. He is a British environmentalist, naturalist, and journalist who wrote “The Moth Snowstorm: nature and joy” in which he describes a German study of 63 nature reserves in Germany that have shown a 76% decline in the biomass of flying insects in the last 3 decades. His book title refers to years ago when he would turn on his headlights to drive in the summer and there would be so many moths and other flying insects that it looked like driving in a snowstorm looks. Made me think back that I used to be fanatic about cleaning my windshield in the summer and I no longer have to clean it very often. I bought the book but haven’t ready it yet. the following Saturday, May 26, Curt Stage of Paul Smith’s College wrote an article in the New York Times “the Silence of the Bugs” in which he writes about the German study and his on work on phytoplankton communities in lakes changing. Stager lists several hypotheses about possible causes and agricultural chemicals including pesticides is one and the most likely main culprit. Here is a link to the “On Being” episode with Michael McCarthy
    Here’s a link to the May 26 NY Times article by Curt Stager:

    June 29, 2018 at 10:00 am

    • Thank you so much, Peter. I recently became aware of the German research. I’m glad there’s at least some awareness. Thank you for your references!

      June 30, 2018 at 7:25 am

  8. Jon Binhammmer

    In Vermont, at least, the amount of habitat destruction, spread of monoculture crops, and urbanization in the last four decades has been too incremental to account for a 45% loss of invertebrates, which leads me to think that the culprit is the neonicotinoids. We need another Rachel Carson, because this is literally leading to another Silent Spring.

    June 29, 2018 at 10:04 am

  9. Kathy Schillemat

    Very timely article, Mary, and thanks for the link to citizen science projects. I pay a lot more attention these days to the native pollinators and love to watch them do their important work. If only people knew how important they are.

    June 29, 2018 at 11:08 am

  10. Bill on the hill

    I would have to concur with you Mary & others commenting on this subject. Here in the highlands of n. central Vt. I have noticed the decline of insects in general in my fields. Honey bees have been close to non-existent for numerous years now & I haven’t seen many bumble bees this season either.
    Plenty of mosquitoes & ticks though!

    June 29, 2018 at 11:46 am

    • Alice Pratt

      That is so very sad……..😢

      June 29, 2018 at 7:26 pm

  11. So pleased you recommended the Xerces Society, such a fine group supporting ‘lowly’ invertebrates. Such a risk in ignoring them. SC

    June 29, 2018 at 5:22 pm

  12. Lyn McQuade

    I really appreciated this milkweed article because I’m trying to grow some. Last fall I planted 5 adult milkweeds in my flower garden, and when they formed seed pods, I scattered the “down” all over. This spring I kept watch for results – nothing. I finally gave up and planted flowers, veg’s, etc. Then, two weeks ago, lo and behold, two milkweeds poked their heads up through the newspaper/heavy mulch that covered them. I’ve placed a little fence around each one and monitor them every day, maintaining conditions I researched. Hope I get results that will address concerns in Mary’s post. Remember when milkweeds really were considered despicable weeds? Even cows wouldn’t touch them as evidenced by their stand-alone presence in pastures. Our natural world is so intertwined and more understanding of it so necessary!

    June 29, 2018 at 6:05 pm

  13. Glenn McKee

    Yes, this is so evident by both observation and survey data. Agricultural practices are a major cause of populations collapsing. Another is the assault on the atmosphere inflicted daily by ongoing climate engineering programs. The “cloud planes,” as I call them, spray aerosolized nanoparticles of aluminum, strontium, barium, and other elements. Observant people see the linear, often criss-crossing spray paths widen out into unnatural, filamentous cirrus-like clouds that render a blue sky hazy white: our new form of “high clouds.” These nanoparticles settle to earth on insect food sources and the insects themselves. These ever-increasing spray programs serve their managers in a number of known ways, but they are destroying life in many more ways. For trustworthy information on this subject, please visit

    June 29, 2018 at 9:52 pm

    • Thank you for this valuable insight, Glenn.

      June 30, 2018 at 7:37 am

  14. Thanks Mary for this important update on insects and arthropods. Citizen Science program are so important. Here’s my latest Citizen Science interest re: fireflies. Anyone in New England and other parts of the USA can participate. Here is the link.
    Thanks everyone AND consider taking part in some Citizen Science program. So important.

    June 30, 2018 at 8:40 am

    • Suzanne Weinberg

      Barbara, I’ve been taking part in this firefly project too. The Mass. Audubon info is much less thorough than the old Museum of Science info was. I’ve got abundant fireflies here in southern Vermont, but nothing like in my childhood in Maryland in the 1950s.

      June 30, 2018 at 11:11 am

    • Suzanne Weinberg

      Barbara, where are you observing?

      June 30, 2018 at 11:11 am

  15. David Fedor-Cunningham

    We can start to reverse the loss of insect and bird life simply by purchasing and growing organic food and ornamentals that are grown without the use of dangerous pesticides and herbicides. Also we can plant a diversity of plants so that their flowering is staggered offers up pollen and nectar over a long period of time with a focus on native plants. Lastly all of us need to push for the complete ban of neonicotinoids as quickly as possible.

    June 30, 2018 at 9:43 am

  16. Suzanne Weinberg

    Mary, can you confirm or refute whether or not bees tend to get “tanglefoot” in milkweed? I’ve heard that this is deadly to honeybees. One beekeeper told me and I have not researched the topic. We have a lot of milkweed, but — alas — hardly any monarchs and zero honeybees for many years.

    June 30, 2018 at 11:09 am

    • Suzanne Weinberg

      Just signing up for replies, as I messed it up.

      June 30, 2018 at 11:16 am

    • Hi Suzanne,
      I wouldn’t say honeybees “tend” to get caught in the flowers, but I have seen them succumb after doing so. As far as I know, they are no more or less likely to get their feet caught than any other insect that visits milkweed flowers, but I have no hard information that I’m basing this reply on!

      July 5, 2018 at 4:57 pm

  17. I am noticing the same thing in central Maine. My pollinator garden, usually humming with excitement, is generally empty despite the blooms. My porch light is attracting very little insect life at night. No moths at my windows. My neighbors all have organic gardens and no lawn treatment. I am involved in the bumblebee atlas in Maine, but it seems that we need to find a way to monitor the less charismatic species as well, and soon.

    June 30, 2018 at 3:59 pm

  18. So distressing. I fear for this world as it seems the Sixth Extinction truly is upon us. 😦

    June 30, 2018 at 10:30 pm

  19. All of the insects you all aren’t seeing must have decided to come into my yard. My peach trees have an 100% infestation of plum curculio, there are all sorts of bees and wasps flying around, and fire ant mounds are dotting my yard.

    July 1, 2018 at 9:24 am

  20. Joel Huberman

    Mark, I think you’re an outlier. Unfortunately, I have to confirm the stories told by others: I’m not seeing nearly as many insects now as I used to. For me the saddest decline is in the beautiful fluorescent blue damsel flies that used to be extremely abundant, flitting around the pickerel weeds on our small lake in southwestern NH. Last summer they were less frequent, and this summer they’re hard to find. The frequency of dragon flies is also markedly lower this year.

    I’m less sad–but nevertheless sad–about the decline of mosquitoes in our area. I’m one of those people that mosquitos really like, so the decline has been something of a relief. But that relief doesn’t compensate for the sense of foreboding that the absence of these annoying insects arouses in me.

    Finally, I want to comment that ticks, which are not insects, are increasingly abundant in our area. I and my hiking companions frequently find them on our clothes after ventures into the woods. That was not true just a few years ago.

    July 10, 2018 at 9:04 pm

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