National field report July 16, 2026

The largest current group is closing: 69% of covered U.S. ZCTAs.

The latest verified release places 23,181 of 33,565 covered ZCTAs in the modeled preventive window closing band. The report rebuilds daily from the same citable GDD release used by the public data product.

Check your ZIP's live status See all 50 states

The national pulse

The current distribution across four modeled timing bands

Below 800 GDD50

8.5%

Too early

2,850 ZCTAs

800–1,000 GDD50

7.2%

Approaching

2,410 ZCTAs

>1,000–1,300 GDD50

15.3%

Open

5,124 ZCTAs

Above 1,300 GDD50

69.1%

Closing

23,181 ZCTAs

National median 1,666.5 GDD50

The midpoint covered ZCTA is preventive window closing.

Geographic spread 861.7–3,400

The 10th–90th percentile range shows the current national geographic spread.

Station fallback 6,371 ZCTAs

Used a fresher alternate station in public release 2026-07-16.

Reusable national image

State medians show how the window differs across the country

State color is based on the median GDD50 among covered ZCTAs, while the all-state table preserves each state's full distribution. State medians can hide local elevation, coastal, lake, urban, and station-to-station variation.

PNG 1200 × 630 share image SVG scalable publisher graphic CSV accessible 50-state dataset

Twelve states to watch

A closer look at twelve geographically varied states

Open

Michigan

Median 1,167.4 GDD50; 40.4% open, 16.7% approaching, and 21.9% closing across 992 covered ZCTAs.

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Closing

Ohio

Median 1,542.9 GDD50; 10.1% open, 2.7% approaching, and 86.3% closing across 1,233 covered ZCTAs.

Open Ohio's ZIP tool

Open

Wisconsin

Median 1,135.7 GDD50; 51.2% open, 22.1% approaching, and 16.3% closing across 783 covered ZCTAs.

Open Wisconsin's ZIP tool

Open

Minnesota

Median 1,146.9 GDD50; 45.1% open, 18.8% approaching, and 22.4% closing across 880 covered ZCTAs.

Open Minnesota's ZIP tool

Open

New York

Median 1,131.6 GDD50; 44.4% open, 22.4% approaching, and 28.2% closing across 1,826 covered ZCTAs.

Open New York's ZIP tool

Open

Massachusetts

Median 1,183.8 GDD50; 62.5% open, 16.3% approaching, and 15.4% closing across 539 covered ZCTAs.

Open Massachusetts's ZIP tool

Open

Connecticut

Median 1,239.8 GDD50; 52.8% open, 0.7% approaching, and 42% closing across 288 covered ZCTAs.

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Approaching

Maine

Median 904.9 GDD50; 20.8% open, 47.8% approaching, and 0% closing across 427 covered ZCTAs.

Open Maine's ZIP tool

Approaching

North Dakota

Median 929 GDD50; 29.8% open, 45% approaching, and 0% closing across 389 covered ZCTAs.

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Approaching

Oregon

Median 903.8 GDD50; 29.9% open, 20.3% approaching, and 9.3% closing across 428 covered ZCTAs.

Open Oregon's ZIP tool

Too early

Washington

Median 789.1 GDD50; 23.3% open, 16.7% approaching, and 9.6% closing across 605 covered ZCTAs.

Open Washington's ZIP tool

Open

Colorado

Median 1,276.7 GDD50; 12.3% open, 9.3% approaching, and 49.6% closing across 528 covered ZCTAs.

Open Colorado's ZIP tool

Read this before treating

A phenology signal is not a pesticide prescription

This report maps this site's operational 800–1,300 GDD50 bands. Those cut points are a broad planning cue tied most directly to Japanese beetle seasonal development—not a universal, research-validated application threshold for every grub species, active ingredient, lawn, or state.

Before using any pesticide, read and follow the current label on your container. It controls the allowed site, target pest, timing, rate, watering, application frequency, setbacks, and safety precautions. Product registrations and state restrictions can change. Confirm active grubs and consult local Extension guidance when species or timing is uncertain.

EPA: how to read legally enforceable pesticide labels

All-state summary

Every state, the same verified public release

Status is assigned from each state's median ZCTA GDD50. The four count columns show the underlying within-state distribution so a median does not masquerade as a uniform state.

Modeled preventive grub-control timing by state, generated July 16, 2026
State	Median GDD50	10th–90th pct.	Modeled status	Too early	Approaching	Open	Closing	Available ZCTAs
Alabama AL	2,951.6	2,244.1–3,351.8	Closing	0	0	22	634	656
Alaska AK	169.4	25.4–386.8	Too early	245	0	0	0	245
Arizona AZ	3,473.1	1,279.3–5,054.6	Closing	11	12	23	370	416
Arkansas AR	2,660.6	2,167.2–3,101.1	Closing	6	0	0	608	614
California CA	2,445.4	1,273.6–3,170	Closing	101	32	57	1,613	1,803
Colorado CO	1,276.7	265.4–1,783.4	Open	152	49	65	262	528
Connecticut CT	1,239.8	1,059.1–1,438.7	Open	13	2	152	121	288
Delaware DE	1,896.8	1,554–1,978.1	Closing	0	0	0	68	68
Florida FL	4,175.5	3,429.8–4,791.1	Closing	0	0	0	1,013	1,013
Georgia GA	2,833.5	2,080.3–3,388.9	Closing	0	0	0	751	751
Hawaii HI	3,909.8	1,305.2–5,051.4	Closing	10	0	0	87	97
Idaho ID	725.7	301.8–1,369.7	Too early	157	51	27	45	280
Illinois IL	1,693.9	1,372.1–2,190.6	Closing	0	5	74	1,317	1,396
Indiana IN	1,659.8	1,341.1–2,011.8	Closing	13	4	61	729	807
Iowa IA	1,482.9	1,176.3–1,730.2	Closing	8	13	136	813	970
Kansas KS	2,051.7	1,547.9–2,389.2	Closing	7	17	31	649	704
Kentucky KY	2,065.3	1,451.5–2,477.1	Closing	0	0	48	731	779
Louisiana LA	3,643	3,046.9–3,872.4	Closing	0	0	0	539	539
Maine ME	904.9	657.9–1,044.6	Approaching	134	204	89	0	427
Maryland MD	1,821.3	1,317.2–2,101.1	Closing	30	0	6	441	477
Massachusetts MA	1,183.8	933.5–1,348.5	Open	31	88	337	83	539
Michigan MI	1,167.4	659.6–1,359.3	Open	208	166	401	217	992
Minnesota MN	1,146.9	691.1–1,356	Open	121	165	397	197	880
Mississippi MS	3,149.2	2,321.1–3,544.9	Closing	0	0	0	427	427
Missouri MO	2,064.4	1,740.9–2,382.5	Closing	2	11	15	1,007	1,035
Montana MT	682	247.5–1,008.2	Too early	245	83	41	0	369
Nebraska NE	1,568.9	1,233.3–1,854.5	Closing	7	20	44	515	586
Nevada NV	1,662.8	468.2–4,152.9	Closing	33	11	19	117	180
New Hampshire NH	1,058.3	715.2–1,191.8	Open	56	40	150	0	246
New Jersey NJ	1,675.1	1,425.7–1,882.6	Closing	0	10	28	560	598
New Mexico NM	1,403.5	475.1–2,973.3	Closing	107	24	37	205	373
New York NY	1,131.6	908.5–1,747.1	Open	92	409	810	515	1,826
North Carolina NC	2,408.3	1,485.5–2,799.9	Closing	16	8	28	801	853
North Dakota ND	929	668.7–1,088.5	Approaching	98	175	116	0	389
Ohio OH	1,542.9	1,267.3–1,884.6	Closing	12	33	124	1,064	1,233
Oklahoma OK	2,918.7	2,209.8–3,116.3	Closing	0	0	0	644	644
Oregon OR	903.8	400.5–1,291.3	Approaching	173	87	128	40	428
Pennsylvania PA	1,362.2	955.9–1,760.6	Closing	38	152	527	1,116	1,833
Rhode Island RI	1,250.9	953.1–1,400.8	Open	0	11	47	23	81
South Carolina SC	2,731	1,994.8–3,217	Closing	0	0	5	419	424
South Dakota SD	1,192.9	843.9–1,414.2	Open	26	58	166	125	375
Tennessee TN	2,198.7	1,666.5–2,796.8	Closing	5	0	5	628	638
Texas TX	3,650.1	2,777.1–4,309.3	Closing	0	13	0	1,976	1,989
Utah UT	1,011.8	388.4–1,851.3	Open	102	36	53	108	299
Vermont VT	853.7	628.4–1,114.7	Approaching	107	80	78	0	265
Virginia VA	2,009.1	1,287.5–2,345.6	Closing	8	21	72	802	903
Washington WA	789.1	400.6–1,262.3	Too early	305	101	141	58	605
West Virginia WV	1,587.2	1,264.1–1,980.9	Closing	2	18	112	606	738
Wisconsin WI	1,135.7	794.2–1,350	Open	81	173	401	128	783
Wyoming WY	797.7	215–1,160.4	Too early	88	28	51	9	176

Need the values in a newsroom or analysis workflow? Download the CSV with dates, counts, percentiles, and state-tool URLs.

Method & uncertainty

How the report was generated

Start with the verified public GDD release

The report derives every claim from public release 2026-07-16. It contains 33,642 nationwide ZCTA rows; this 50-state report includes 33,565 fresh values. The source release keeps 20 unavailable rows explicit instead of substituting stale station data.

Compute one transparent heat index

For each day from January 1, daily GDD50 is max(0, (Tmax + Tmin) / 2 − 50°F). Daily values are summed. This is an air-temperature-derived index from NOAA stations, not an on-lawn soil-temperature reading.

Use a freshness-aware station chain

Each ZCTA can consider up to 8 nearby candidates. The pipeline uses the nearest station with sufficiently fresh Tmax/Tmin data and falls back when a closer station is stale or incomplete. 6,371 reported ZCTAs used a fallback.

Aggregate ZCTAs without erasing the spread

Census ZCTAs are assigned to the state containing their largest land-area share. State status comes from the median GDD50; the table also reports the 10th–90th percentile range and every ZCTA-level band count.

What the model cannot see

Elevation, coast and lake effects, urban heat, shade, snow cover, irrigation, soil moisture and texture, turf condition, beetle species, and local establishment can shift biology. Recent GHCN-Daily records may lag and can later be replaced by archive-quality values. A station-based ZCTA estimate is a planning proxy, not a measurement of an individual lawn.

Read the full site methodology

Preventive is not curative

The ingredient and the grub stage still decide the action

Preventive

Plan before a damaging population of small grubs is established

Preventive active ingredients do not share one national date. Michigan State's 2026 guidance places chlorantraniliprole earlier than imidacloprid examples. The modeled band should prompt a label and local-guidance check, not a brand-agnostic application order.

Curative

Treat confirmed, susceptible grubs—not a red map color

Crossing 1,300 GDD50 does not automatically call for trichlorfon or another rescue treatment. Confirm live grubs, species or stage, and actual injury. Late rescue control can be partial once grubs are large.

Primary sources

Research and first-party guidance behind the framing

Ebbenga et al. (2022) Field-validated Japanese beetle adult phenology modeling.
Ohio State Phenology Calendar Adult emergence marker; not a pesticide threshold.
Michigan State Extension (2026) Ingredient-specific preventive and curative timing.
University of Minnesota Extension Life cycle, moisture, diagnosis, and treatment distinctions.
UW–Madison Extension Species-specific white grub management windows.
NOAA NCEI GHCN-Daily Daily station Tmax/Tmin and data-quality context.
U.S. EPA pesticide labels Legally enforceable directions and restrictions.
USDA APHIS Japanese beetle Current U.S. distribution context and western limits.

From national signal to local check

Move from the national signal to your ZIP.

This stable report URL follows the latest verified daily release. The ZIP tool shows the current serving value, observation date, and station distance for a specific location.

Check your ZIP's live grub timing