So I’ve been spending a lot of time in my suburban yard in the US Midwest taking pictures of the invertebrate life. I try not to pick favorites and take pictures of everything, but I especially like bees. Now last year, and I could be remembering wrong, I remember seeing plenty of bumblebees, primarily Common Eastern Bumblebees, as ID’d here. This year I am not seeing them. I think I took a picture of one in May but that’s it. I saw one in another city yesterday but it was too far for a photo. I am still seeing wasps, so this is good, but even then I don’t see the larger ones I usually see. Most of the insects I see pollinating are ants, calligraphers, drone flies, and lots of little green Cuckoo wasp family wasps. My Philadelphia fleabane was a big hit with small native bees in the spring but it is done flowering. Right now, I have plenty of native plants in bloom like compass plant and coreopsis, and some non-native annuals so lack of flowers shouldn’t be an issue. It got extraordinarily hot fairly early this year, too. The number of butterflies in my yard so far is down too. Other than cabbage white I have only seen a single tiger swallowtail and I do grow milkweed for monarchs and carrots for swallowtails (and me). Is it too early in the season or should I be concerned that they are declining this fast? Or maybe they simply aren’t in my yard this year having found a yard with more flowers, maybe?
First, one year does not make a trend. It’s good to be aware of different groups and availability of similar habitat in the neighborhood. Also, do you rake or use a leaf blower in the fall? That could disturb Bombus nests.
I’m only in the second year of observing my garden in New Mexico. Overall insect numbers (both populations and diversity) continue to rise as I spend time outside, but I have noticed fewer Melissodes this year and many more Lithurgopsis. Some days, I see 6 or 8 Bombus pensylvanicus workers and others (like today) I see one queen. I’d say butterflies are about equal to last year, while I see more moths and flies.
While it is true that one year does not make a trend, sudden conspicuous changes (e.g. population declines) could be cause for concern, particularly if it is over a broad area/region rather than a single site.
I too have noticed an unusual lack of Bombus spp. in the Chicago area (ditto for Carpenter bees). Having been to a few of the larger prairie nature preserves in the area, I must say that it is a little eerie to spend several hours hiking over ~300 acres of remnant and restored prairies and to neither see nor hear a single bumblebee in late June. In previous years these places (dozens of miles apart) were literally buzzing with activity. The weather conditions have been very hot and dry lately and the spring was unusually cold , but there was not an overall lack of floral resources in prior months. I do see some cabbage white butterflies, the usual flies, very few swallow tails, and fewer than usual smaller bees and wasps.
Even in my backyard native garden (usually crawling with bees on Asclepias tuberosa, Ruellia humilis, Echinacea purpura, Drymocalis arguta, Dalea purpurea and candida at this time), I’ve seen a bumblebee fewer than 6 times this year.
Last year and this year are quite different years, last year warmed up early and I had 9/10 species of local Bombus in April. This year the wet cold spring appears to have slowed everything down quite a bit, not helped that we’re still feeling the effect of the drought. 2019 was also a wet cold spring and slowed everything down. Currently, I’ve got all ten local species across my sites, but the workers aren’t out in force yet for several species. There could be quite a few reasons for what we’re seeing this year, so I wouldn’t worry until we see what the later part of the year looks like. And next year could be quite different again.
For what it’s worth (not much), I’m seeing a normal number of bumblebees here in Massachusetts in the US. My understanding from talking to professional entomologists is that insect populations vary quite a lot from year to year, at least ten-fold, if not more. So I wouldn’t panic just yet. Are other iNatters posting bumblebees photos from your region this year? Was it particularly wet/dry/stormy last year, when this year’s queens would have been produced? I’m seeing fewer dragonflies and damselflies here than “normal”, but last year it rained for three weeks in July, so maybe the tenerals and adults were literally beaten down by the heavy rain.
You might be interested in this report (PDF) as it tracks bee abundance over multiple years. On p. 32, they discuss weather patterns as likely causes of fluctuating numbers of some Bombus. But that report is very simplistic. This study (PDF) is more thorough in their analysis, and suggests that “bee abundances were driven primarily by the indirect effects of climate on the temporal distribution of floral resources”.
“We used structural equation modelling to test the importance of direct and indirect (via floral resources) climate effects on the interannual abundance of three subalpine bumblebee species. In addition, we used long-term data to examine how climate and floral resources have changed over time. Over 8 years, bee abundances were driven primarily by the indirect effects of climate on the temporal distribution of floral resources. Over 43 years, aspects of floral phenology changed in ways that indicate species-specific effects on bees. Our study suggests that climate-driven alterations in floral resource phenology can play a critical role in governing bee population responses to global change.”
I’m going to speculate that what you grow in your one yard has little effect on insect abundance in your area overall. Insect population ecology is going to be acting on a larger scale. What you plant will impact what you see (they’ll likely be attracted to your yard)–but one yard won’t impact insect abundance at the scale that impacts insect populations. So, even though your plantings may be consistent year after year, you’ll see fluctuations in numbers due to those larger-scale impacts such as climate or floral abundance in the surrounding area (which could be over a hundred square miles).
I’ve been observing in the same area of the Red River in Winnipeg for a number of years now. It is my sense (subjective) that invertebrate numbers are lower than a couple of years ago. I live in an environment that is prone to huge climactic changes. For example, last year we had little snow going into the summer (with about average winter temperatures) and then a drought. Very little rain, and lots of heat. This winter was very cold, with a lot of snow. Spring has been cool and wet.
I have noticed over the years that non-human life populations fluctuate. I’ve seen very few butterflies or bees. The local bird population seems a bit lower too. Very few dragonflies. I suspect it is a combination of climate, and general life cycles. About 5 years ago we had an infestation of Forest tent caterpillars that denuded trees. The next year there were none, which is typical of the long term cycle of these moths.
I guess what I’m trying to get at is that what we observe can be subjective. It may or may not indicate a larger trend in populations. There are so many variables…
I noticed last year that my vegetable garden was not being visited very often by pollinators and the harvest was very low. This year, I planted native wildflowers (a variety so I will have blooms throughout the growing season) with the vegetables and I’m seeing a lot more pollinators, including bumblebees, plus the harvest has improved greatly.
Insect populations are naturally very cyclic. One year decline is nothing to be concerned about. It would take studies of populations over many decades to really determine if there is a sharp downturn.
I wonder if hot and dry weather might be at least part of the reason. I’m just now getting an appreciation for how much local weather can influence insect populations. My yard has gone without rain for quite a while and just over the last couple of days started getting some thunderstorms. Along with that, I’m seeing a marked increase in insect activity, both in terms of diversity as well as numbers. I’m seeing the digger bees under my shed are back so that’s good, but don’t remember seeing a lot of other bees. Mostly I’ve noticed predatory flies (like robber flies), wasps hunting for other insects, and lots of beetles.
The main event today appears to be an explosion of Japanese beetles. Just a few days ago, there were none whatsoever and I was wondering where they were as they usually appear in June around my yard. Today they were everywhere and I’ve collected more than ever in a single day. I’m guessing the dry spell kept them underground since the hard clay soil in our area would make it difficult to dig through (part of the reason I’ve put off yard work until we got some rain). But now that the rain has soften the topsoil enough, they seem to be emerging in larger than usual numbers.
Thanks. I am hoping to more once the garden flowers really take off at the end of the month. I know things can fluctuate year to year but it just seems like an overall downward trend. Of course that’s what I hear on the news too so it might be a little confirmation bias. :)
I’d be careful about using the news as a source for declines, they have a very bad habit of not giving the full context of articles and studies that are being discussed and frequently when talking about bees, they tend to treat all bees as Honey Bees, which can be further misleading.
I would add to the excellent comments here that in the urban/suburban setting, relatively small changes to the local ‘built environment’ can have a noticeable effect on who or what shows up in your yard; for example, a nearby overgrown vacant lot can be home to all kinds of pollinators that disappear once a building goes up there.
I’ve seen very, very few in my usual haunts which have no new development nearby. That includes a seven hundred acre nature preserve where I spent an hour recently and saw only one bumble bee and only three butterflies. I’m hoping things pick up in July. We had a late, cold spring followed by heat waves and droughty conditions.
I only ever saw one Bombus and that was 5 months ago and I live in Istanbul Turkey so maybe there is a slight global drop in population? Or maybe not, it could just be coincidence that I haven’t noticed any.
I was thinking about that too. They are building a house nearby so perhaps that has disrupted things extra for my area. I read on a pest control site that carpenter bees don’t like strong vibrations (not that I blame them). Perhaps this is true of other bees are well?
It was very wet last year. Super duper monsoon level wet in the spring with tons of flooding and then hot in the Summer like we’d never had before. So perhaps last year was especially unkind to them. This year has been weird too although I don’t think quite as extreme.
Yeah, I try to be extra cautious about that, but it can be hard and you have to take away that news sources often have an agenda, too. But I would like to assume the more reputable sources at least base things on fact. Trust no one can be frustrating too. That said, it’s been said for years that there’s an overall decline in insect diversity and that bumbles are in trouble. I do remember there being more as a kid, but I also wasn’t as aware of which kinds they were. They were all “bees” and big fuzzy bumblebees (which may have been carpenter bees too). And my memory could be not quite accurate too. But I also remember being able to see the stars along the highway and having lots of snow every winter instead of just some winters so I might not be crazy.
The “save the honey bees” ads drive me nuts because I’m like, hey save all the pollinators!
We are pretty new at observing. In the greater Minneapolis-St. Paul region, we have been visiting remnant and restored prairies for the past several weekends, as well as local patches daily, and observing typically 0-1 individual Bombus. In looking at our iNat records from last year, we were not reporting Bombus in number until the second week of July. So we cannot make comparisons yet. When we photographed a Rusty-patched Bumblebee in mid-June, a college entomologist speculated that it must be a queen due to how early it was.
Now that we are observing other kinds of bees (mining, sweat, furrow, longhorn, etc.), we have some records for this year to compare with next year.
We were planning to disturb a large patch of Common Snowberries to plant more diverse species but noticed two individual bees nesting in the leaf litter. We have decided to leave the patch since the habitat is proving useful. We plant elsewhere where there is turf grass.