Something has been happening in the sky over Northern California this summer, and on Saturday it reached Lawndale Road.
A large swarm of dragonflies was seen over the road on 15 August. No count was taken, and no species identified — which, as it turns out, is fine. The interesting thing about the Lawndale Road swarm is not what it was. It is that it was the last stop on a line that runs the length of Northern California.
The valley is late to this. SFGATE’s Anna FitzGerald Guth traced the same phenomenon up and down the region: hundreds overhead at a ranch near Smith River in mid-July, near the Oregon line; two weeks later a swarm over Guerneville, with a mating pair riding the brim of a friend’s hat on a tubing run down the Russian River; then squadrons over the grassy hill by Fairyland at Lake Merritt in Oakland. In San Francisco, Recreation and Park staff reported an “unusually large number of dragonflies” over Dolores Park one weekend. On Reddit, r/SanFrancisco and r/bayarea both had versions of the same question: what is with all the dragonflies this year?
Lawndale Road is the same question, arriving late and inland.
Three different things are being seen, and they are getting confused
The answer is not one answer, which is why the explanations circulating sound contradictory. Three separate things produce a crowd of dragonflies, and only one of them is going anywhere.
They are emerging. Lynn Kimsey, professor emerita at UC Davis and former director of the Bohart Museum of Entomology, told SFGATE that eggs laid in water hatch as the days lengthen and warm; the nymphs then leave the water and shed their skins. That is why adults become conspicuous from June through August. The dragonflies were always there. They were underwater.
They are hunting. Kimsey draws the distinction that settles most sightings: a swarm over a field or grassy ground is feeding, while dragonflies hovering over water are mating or laying eggs. Chris Grinter, senior collection manager of entomology at the California Academy of Sciences, told SFGATE that cool weather, wind currents and “an abundance of food (mosquitoes)” are the likely drivers of this year’s numbers.
They are formidable at it. A dragonfly flies at up to 35 mph, catches about 95% of the prey it goes after — often in mid-air — and eats hundreds of mosquitoes, gnats and flies a day. A swarm working the air over a road is unpaid pest control.
They are migrating — but not yet. That is the autumn event, and it is the one worth marking your calendar for.
On the evidence, Lawndale Road was the second kind. The date settles it: the migration is a September and October event, so a swarm on 15 August was feeding, whatever it was hunting over.
What the valley’s own record says
The Wag’s field guide is built from every research-grade sighting logged inside the valley, and on dragonflies it holds 711 observations across 40 species — more species in this one valley than the “over 28” usually quoted for the whole Bay Area, which suggests the regional figure is a conservative one.
| Month | Apr | May | Jun | Jul | Aug | Sep | Oct |
|---|---|---|---|---|---|---|---|
| Share of valley sightings | 20% | 29% | 21% | 11% | 7% | 3% | 1% |
This does not quite match the June-to-August emergence window. The valley’s record peaks in May and is well down by August. Before reading anything into that, note the caveat: these are sightings, not dragonflies. May is also when people are out walking with a phone. The same bias runs through the valley’s bird records, where an April–June spike turned out to be birdwatchers rather than birds. What the table shows for certain is that a large swarm over one road on 15 August is a local abundance against a falling curve — not more dragonflies in the valley, but the remaining ones all in one place, because that is where dinner was.
The autumn passage, and the nine species to watch for
September and October bring the other kind of swarm, and this one has somewhere to be. Migrating dragonflies use the same coastal flyway as the hawks and falcons, and since 2014 counters at the Golden Gate Raptor Observatory have logged them alongside the raptors over the Marin Headlands. On one October 8th they recorded 269 Variegated Meadowhawks moving south in a single day.
Bay Nature counts at least nine species making that passage. Here is the part that should interest anyone wondering whether the valley sits on the route: all nine have been logged here.
| Species | Valley sightings | |
|---|---|---|
| Flame Skimmer | 56 | the big orange one everybody notices |
| Variegated Meadowhawk | 38 | the migration’s headline species |
| Cardinal Meadowhawk | 28 | red, and holds its wings forward |
| Blue-eyed Darner | 12 | |
| Twelve-spotted Skimmer | 8 | |
| Black Saddlebags | 7 | dark patches at the hind wing base |
| Common Green Darner | 4 | the long-distance traveller |
| Spot-winged Glider | 1 | |
| Red Saddlebags | 1 |
Only about 16 of the 326 dragonfly species in the United States migrate at all, and the ones that do are serious about it: Common Green Darners average more than 600 kilometers, and individuals have been tracked beyond 2,500. A tenth species deserves its own line — the Wandering Glider, logged once in the valley, occurs on every continent except Antarctica and crosses oceans on wings built for the job.
Where these insects are going, and where they started, is still unknown. Bay Nature is direct about it: the details along the West Coast “remain subjects of surmise.” That is a strange and rather cheering thing — a large, conspicuous, daylight-flying animal migrating over our heads on a route nobody has mapped.
If you see one
- Holding station over grass or a road — a feeding swarm. It will move on when the insects do.
- Hovering over water — mating, or laying the eggs that produce next summer’s swarm.
- All moving the same direction, in September or October — that is the migration, and the Wag would like to hear about it: [email protected].
Either way, log it. Every sighting in the table above came from a resident with a phone camera, and the valley’s entire dragonfly record is 711 observations deep. That is thin enough that one good afternoon on Lawndale Road would move it.
Regional reporting, and the interviews with Chris Grinter, Lynn Kimsey and Daniel Montes, from SFGATE (Anna FitzGerald Guth). Migration counts from Bay Nature. Swarm behavior and migration distances from Bryan Pfeiffer. Valley species counts and monthly figures from the Wag’s field guide, built on research-grade iNaturalist observations inside the valley, retrieved 16 August 2026.