Back to the trend of the day: Los Angeles is fighting its worst mosquito season in a decade

Poly Rating · from the trend of the day

Worst Mosquito Cities in US 2026 vs West Nile Risk

Los Angeles has topped the mosquito-treatment list six years running, yet the highest West Nile rates per resident are in North Dakota (2.76 per 100,000) and Nebraska (2.49), and neither has a city in the top 10.

No. 1: Denver, CO
10 places
Current as of October 20, 2026, 17:54 EDT

01Final list

The leading AIs each built their own list of ten independently. Here is one result that is easy to check: every place has a reason, a source, and the list of AIs that included it.

Order: from most to least AI agreement.

A bright badge means this AI put the entry on its list. A dim badge means it did not.

1
Denver, CO
10th for treatments in 2026, while Colorado's West Nile count swings widely: more than 600 cases in 2023, then 76 in 2024. An older Orkin list put Denver 38th.
Included it: Gemini, Claude, ChatGPT.
In their lists: Gemini: 6 · Claude: 2 · ChatGPT: 10
What each AI noted 3
- Geminiplace 6
  Occupies a modest #38 on pest control lists, but endured an unprecedented 5.38 neuroinvasive cases per 100,000 residents in peak outbreak cycles.
  Source ↗
- Claudeplace 2
  Denver is 10th for treatments, but Colorado went from 76 human cases in 2024 to more than 600 in 2023.
  Source ↗
- ChatGPTplace 10
  Denver completes Orkin’s 2026 top ten; treatment rank alone cannot tell whether its human West Nile rate is high or low.
  Source ↗
3 AIs put it here
Source ↗
2
Atlanta, GA
Fifth for treatments in 2026 and No. 1 from 2015 to 2020, yet Georgia is not among CDC's highest-incidence states. No metro rate was found.
Included it: Gemini, Claude, ChatGPT.
In their lists: Gemini: 4 · Claude: 5 · ChatGPT: 5
What each AI noted 3
- Geminiplace 4
  A historic hub for backyard mosquito spraying that records less than 0.15 severe neuroinvasive cases per 100,000 residents.
- Claudeplace 5
  Atlanta held Orkin's top spot from 2015 to 2020 and is still 5th, a Southeast city whose WNV record I could not retrieve.
  Source ↗
- ChatGPTplace 5
  Atlanta led Orkin’s list for six consecutive years from 2015 through 2020; it is fifth in 2026.
  Source ↗
3 AIs put it here
Source ↗
3
Washington, DC
Sixth for treatments in 2026, up two places (another edition had it 7th). No metro West Nile rate was found to compare.
Included it: Gemini, Claude, ChatGPT.
In their lists: Gemini: 8 · Claude: 7 · ChatGPT: 6
What each AI noted 3
- Geminiplace 8
  Ranks #7 in household treatment volume driven by suburban container breeders, but ranks #41 in per-capita neurological disease.
  Source ↗
- Claudeplace 7
  DC is 6th for treatments, with a metro WNV rate I could not retrieve.
  Source ↗
- ChatGPTplace 6
  The D.C. metro climbed two places to sixth on Orkin’s treatment-demand list.
  Source ↗
3 AIs put it here
Source ↗
More about the top three ↓
4
Los Angeles, CA
No. 1 for treatments six years running. 2026 is its worst West Nile year in a decade, with 100 cases by 22 Sept against about 41 a year, so the gap is closing.
Included it: Gemini, Claude, ChatGPT.
In their lists: Gemini: 10 · Claude: 8 · ChatGPT: 1
What each AI noted 3
- Geminiplace 10
  Held #1 on Orkin's list for four straight years due to daytime Aedes bites, but saw West Nile surge tenfold in 2026 to over 200 cases and 10 deaths.
  Source ↗
- Claudeplace 8
  LA is Orkin's No. 1, and 2026 is its worst WNV year in about a decade: 100 cases by 22 Sept against a usual 41 a year.
  Source ↗
- ChatGPTplace 1
  Orkin’s No. 1 mosquito-treatment metro coincides with a sharp local outbreak: the county reported 34 cases and 2 deaths in 2024, while 2026 reporting describes a much larger season.
  Source ↗
3 AIs put it here
Source ↗
5
New York, NY
Third for Orkin treatments in 2026, yet New York is not among the highest West Nile states, which are led by North Dakota at 2.76 per 100,000.
Included it: Gemini, Claude, ChatGPT.
In their lists: Gemini: 3 · Claude: 6 · ChatGPT: 3
What each AI noted 3
- Geminiplace 3
  Holds the #3 spot nationwide for commercial mosquito contracts, while human West Nile neuroinvasive incidence sits near the bottom of all US metros.
  Source ↗
- Claudeplace 6
  New York is 3rd for treatments. National WNV rates are highest in the Plains and Mountain states, not the Northeast.
  Source ↗
- ChatGPTplace 3
  New York ranks third for Orkin treatments, a measure shaped by customer demand and service coverage as well as mosquitoes.
  Source ↗
3 AIs put it here
Source ↗
6
Detroit, MI
Fourth for treatments in 2026, up one place. With no metro West Nile rate found, it sits only on the nuisance side of the gap.
Included it: Claude, ChatGPT. Did not include: Gemini.
In their lists: Claude: 4 · ChatGPT: 4
What each AI noted 2
- Claudeplace 4
  Detroit ranks 4th on the treatment list; I found no metro WNV rate to set against it, so it is placed on the nuisance side only.
  Source ↗
- ChatGPTplace 4
  Detroit rose one place on Orkin’s year-over-year list to No. 4, but the list does not measure disease risk.
  Source ↗
2 AIs put it here
Source ↗
7
Dallas–Fort Worth, TX
Eighth for treatments. Dallas County went from 3 West Nile cases in 2022 to 37 in 2024, though the county's own case table lists only 7.
Included it: Claude, ChatGPT. Did not include: Gemini.
In their lists: Claude: 3 · ChatGPT: 8
What each AI noted 2
- Claudeplace 3
  Dallas County reported 3 human cases in 2022 and 37 in 2024, a swing within a city that sits 8th on the treatment list.
  Source ↗
- ChatGPTplace 8
  Dallas is eighth on the 2026 list; Orkin’s older methodology explicitly included residential and commercial treatments, while its 2026 release specifies residential treatments.
  Source ↗
2 AIs put it here
Source ↗
8
Chicago, IL
Second for Orkin treatments in 2026, yet Illinois is not among the top West Nile states. No metro rate per 100,000 was found.
Included it: Claude, ChatGPT. Did not include: Gemini.
In their lists: Claude: 10 · ChatGPT: 2
What each AI noted 2
- Claudeplace 10
  Cleveland is 9th for treatments, with no WNV rate retrieved.
  Source ↗
- ChatGPTplace 2
  Chicago is second on Orkin’s treatment list; the CDC’s county series makes clear why treatment rank alone cannot stand in for West Nile risk.
  Source ↗
2 AIs put it here
Source ↗
9
Phoenix, AZ
Only 40th of 50 for Orkin treatments, yet Maricopa County logged 1,487 West Nile cases in 2021 (local reports said 361 by October) and just 3 in 2020.
Included it: Claude. Did not include: Gemini, ChatGPT.
In their lists: Claude: 1
What each AI noted 1
- Claudeplace 1
  Orkin puts Phoenix 40th of 50, yet Maricopa County had 1,487 West Nile cases in the 2021 outbreak and only 3 in 2020.
  Source ↗
1 AIs put it here
Source ↗
10
Omaha, NE
Not in Orkin's 2026 top 10, while Nebraska had the second-highest neuroinvasive West Nile rate in 2024 at 2.49 per 100,000. That is a state figure, not a metro one.
Included it: Gemini. Did not include: Claude, ChatGPT.
In their lists: Gemini: 1
What each AI noted 1
- Geminiplace 1
  Ranks outside the commercial top 50 for yard treatments, yet faces the nation's second-highest per-capita rate of neuroinvasive West Nile disease.
  Source ↗
1 AIs put it here
Source ↗

02More about the top three

The ranking is above. Here is more about the three places at the top: what they are, why they are here, and what is worth knowing.

The ranks count mosquito treatments, not West Nile illness, and the West Nile figures are for whole states or other years, not cities.

1Denver, CO

No. 1 — Denver, CO. On the lists of 3 of 3 AIs; median place there: 6. AIs ranked it first because its 10th place for treatments hides West Nile cases that swing from 76 to over 600.

Did you know

The Brown Palace Hotel opened in 1892. Guests since then include the actor John Wayne, President Franklin D. Roosevelt and The Beatles.
Source ↗

What it is: Colorado's big city, 10th on Orkin's 2026 mosquito-treatment list.
Its edge: Climbed from 24th in 2019 to 10th, and Colorado's West Nile counts swing hugely.
Who should know: Useful for anyone who thinks a low pest ranking means low West Nile risk.

Orkin treatment rank 202610th for treatments
Founded1858
HeadquartersDenver, Colorado

Wikipedia · Wikidata

Why it is here

Denver ranked 10th on Orkin’s 2026 list, which counts new residential mosquito treatments from March 18, 2025, to March 18, 2026. [Orkin’s 2026 list](https://www.orkin.com/press-room/los-angeles-worst-mosquito-city-again)
Source ↗
Denver entered Orkin’s list at 24th in 2019; by 2024 it was 16th, and in 2026 it reached 10th. [Orkin’s 2019 list](https://www.orkin.com/press-room/orkins-2019-top-mosquito-cities) · [Orkin’s 2024 list](https://www.orkin.com/press-room/2024-top-mosquito-infested-cities) · [Orkin’s 2026 list](https://www.orkin.com/press-room/los-angeles-worst-mosquito-city-again)
Source ↗

Did you know

The U.S. Mint in Denver makes billions of coins each year, which makes it one of the busiest mints in the country. You can take a guided tour to see how coins are made.
Source ↗

History

In 1863, a small fire in a wooden building spread through downtown Denver in high winds, wrecking almost every building there. People rebuilt with brick, and a law required nearly every Denver building to use it—a change still visible in the city today.
Source ↗

Keep in mind

West Nile cases here can jump from year to year. In 2023, 619 people in Colorado were affected and 375 were hospitalized. Denver County had the most cases (95). Treatment counts do not show illness.
Source ↗

Video: Why Denver Is Struggling To Keep Up With Its Economic Boom · CNBC

Compare the top three ↓

2Atlanta, GA

No. 2 — Atlanta, GA. On the lists of 3 of 3 AIs; median place there: 5. AIs put it second for its long history at the top of treatments, though Georgia is not a high West Nile state.

Unknown author Unknown author · Public domain · Wikimedia Commons

Did you know

Atlanta's airport served 108.1 million passengers in 2024. That is second only to its 2019 record of 110 million passengers.
Source ↗

What it is: Georgia's capital, 5th on Orkin's 2026 mosquito-treatment list.
Its edge: Held Orkin's top spot six years in a row, from 2015 to 2020.
Who should know: Useful for readers who want to see that heavy spraying and sickness are different things.

Orkin treatment rank 20265th for treatments
Founded1845
HeadquartersGeorgia

Wikipedia · Wikidata

Why it is here

Atlanta ranked 5th on Orkin’s 2026 list, one place lower than in 2025. The list counts new residential mosquito treatments. [Orkin’s 2026 list](https://www.orkin.com/press-room/los-angeles-worst-mosquito-city-again)
Source ↗
Atlanta held Orkin’s top spot for six straight years, from 2015 through 2020. [Orkin’s 2026 list](https://www.orkin.com/press-room/los-angeles-worst-mosquito-city-again)
Source ↗

History

In 1864, Union forces captured Atlanta, then burned railroad lines and buildings as they left. Much of the city lay in ruins, but Atlanta rebuilt and grew into Georgia’s largest city by 1880.
Source ↗

Keep in mind

Atlanta's high ranking counts pest-control treatments, not sick people. A July 2026 report says Fulton County mosquito samples tested positive for West Nile, and the CDC said US infections were the highest since 2004.
Source ↗

Where to go further

Read this 2 September 2026 news story on West Nile in two Roswell parks. Look first at how crews respond: they treat areas within a quarter-mile of a positive trap.
Source ↗

Video: Why Atlanta Is the Opposite of How a City Should Work · Architales

Compare the top three ↓

3Washington, DC

No. 3 — Washington, DC. On the lists of 3 of 3 AIs; median place there: 7. AIs ranked it third because it is high for treatments, yet no city West Nile rate was found to compare.

Did you know

Wheaton Metro station, just outside Washington, has 230-foot escalators. They are the longest single-span escalators in the Western Hemisphere. They rise 115 feet.
Source ↗

What it is: The US capital, 6th on Orkin's 2026 mosquito-treatment list.
Its edge: Rose two places in the latest list and stayed in the top 10 in both editions.
Who should know: Useful for city residents: public crews treat drains, but yards are left to owners.

Orkin treatment rank 20266th for treatments
Founded1790
HeadquartersUnited States

Wikipedia · Wikidata

Why it is here

Washington, D.C. ranked 6th on Orkin’s 2026 list, up two places from the prior year. [Orkin’s 2026 list](https://www.orkin.com/press-room/los-angeles-worst-mosquito-city-again)
Source ↗
Washington, D.C. ranked 7th in 2024 and 6th in 2026, staying in Orkin’s top 10 across both editions. [Orkin’s 2024 list](https://www.orkin.com/press-room/2024-top-mosquito-infested-cities) · [Orkin’s 2026 list](https://www.orkin.com/press-room/los-angeles-worst-mosquito-city-again)
Source ↗

History

In 1814, British troops burned the U.S. Capitol and other major public buildings in Washington. Congress debated moving the capital, but rejected the idea; rebuilding the House chamber took nearly five years.
Source ↗

Keep in mind

DC Health says that from 2020 to 2024 the District averaged three human West Nile cases a year, all between July and September. That is a small count next to its high treatment ranking.
Source ↗
DC Health treats standing water in public places such as drains and catch basins, but not private property. Residents are left to handle their own yards.
Source ↗

Where to go further

Open DC Health's West Nile overview. Look first at the larvicide part: crews treat sewer drains where mosquitoes breed. Weekly lists of positive spots are on a related page.
Source ↗

Video: The Reason Why DC Is Between Maryland and Virginia · Smithsonian Channel

Compare the top three ↓

The top three side by side

	Denver, CO	Atlanta, GA	Washington, DC
In the AIs' lists	3 / 3	3 / 3	3 / 3
Orkin treatment rank 2026	10th for treatments	5th for treatments	6th for treatments
Founded	1858	1845	1790
Headquarters	Denver, Colorado	Georgia	United States
Put first by	—	—	—

Places with the same number of AIs are ordered by their average place in the AIs' own lists.

03Worth knowing

What the AIs noticed while building the list.

Nationally, the neuroinvasive West Nile rate was 0.40 per 100,000 in 2024 (1,808 cases, 75% neuroinvasive). The top states were North Dakota at 2.76 and Nebraska at 2.49, and neither has a city in Orkin's top 10.

Noticed by:

Included it: Claude, ChatGPT. Did not include: Gemini.

01Final list

Denver, CO

Atlanta, GA

Washington, DC

Los Angeles, CA

New York, NY

Detroit, MI

Dallas–Fort Worth, TX

Chicago, IL

Phoenix, AZ

Omaha, NE

02More about the top three

1Denver, CO

Did you know

2Atlanta, GA

Did you know

3Washington, DC

Did you know

The top three side by side

More ratings

03Worth knowing

04Questions people ask

05How we counted

1The question

2Why this topic

3Where it applies

4What we looked at

5Who ranked

6How the places were set

06Each AI's own list

What Gemini noticed

What Claude noticed

What ChatGPT noticed