National Snapshot

Late July: webs, mites, and honeydew take over

We've shifted from emergence to management season. Japanese beetle is past peak in the South but still active north and in the Midwest, where edge-feeding is climbing. The week's new story is fall webworm — branch-tip webs are just becoming visible, giving a short, high-value window to prune them out small. Meanwhile heat and deepening Northeast drought are pushing spider mites toward their late-summer peak, scale honeydew is coating foliage, and in the Mid-Atlantic spotted lanternfly nymphs are molting into their first winged adults. A humid pattern keeps foliar disease pressure high.

Defoliator

Japanese beetle still active nationwide though past peak in the South; skeletonizing linden, rose, and grape. Emergence continues until ~2,150 GDD, and Midwest edge-feeding is intensifying.

Caterpillar

Fall webworm — the new arrival this week. Small silken webs are appearing on branch tips (larvae have fed 3–4 weeks unseen). Prune them out now while nests are small.

Sap feeder

Scale & honeydew building: cottony camellia and lecanium scale are coating foliage in honeydew and sooty mold; magnolia and Japanese maple scale crawlers approach in August. Crapemyrtle bark scale heavy in the South.

Mite

Spider mites escalating in the heat and drought — oak, two-spotted, spruce, and honeylocust mites cause stippling and bronzing. Populations typically peak late July into early August.

Borer

EAB & summer borers in flight (EAB peak passed in late June in warmer areas); clearwing borers active. Deep-water stressed trees, avoid fresh wounds, and don't move firewood. Oregon's EAB zone is expanding.

Disease

Foliar & canker pressure: humid weather is driving cedar-apple rust, powdery mildew, Cercospora, and beech leaf disease, plus honeydew-fed sooty mold.

Methodology Note

Seeing a lower GDD reading than last week? Here's why.

Growing degree days accumulate from January 1 and never decrease — a lower number doesn't mean it cooled off. Starting with this issue, each region's reading is anchored to the latest measured cooperative-extension station data rather than a seasonal estimate, so a figure may step down once as it locks onto the real value. From here forward, readings will only climb week to week. As always, confirm against your nearest local station before timing an application.

Pest on the Chart · This Week

Fall Webworm

Hyphantria cunea

This week's emerging pest. Eggs hatched in late June and larvae have been feeding quietly for weeks; now the tell-tale silken webs are appearing at the ends of branches, first on the south side of the crown. Webbing expands to envelop whole branches as caterpillars grow. Damage is mostly cosmetic on established trees, but nests are unsightly and easiest to manage while small.

Webs Appear

Now → Fall

Key Hosts

Pecan·Cherry

Rx Note

Prune small

℞ — Prune out and destroy small nests as soon as you see them — the single most effective, lowest-input control. For young larvae in reachable webs, Bt kurstaki or spinosad works; open the web first so the spray reaches the caterpillars. Skip burning nests in the tree, which harms the host more than the pest. Tolerate light, late-season nests on large, healthy trees.

Regional Rx · 5 Zones

Read your zone like a chart

Each card reports the region's growing-degree-day reading (the vital sign that drives every timing call), what's active now (Diagnose), and how to time treatment (℞). GDD ranges are typical for the week, base 50°F from Jan 1 — always confirm against your nearest station.

NE

Northeast & New England

ME · NH · VT · MA · RI · CT · NY

GDD · Accumulated

~900–1,300

0

1,500

3,000+

Conditions: GDD averaging ~1,094 (base 50°F) as of July 8 per UMass. Drought is intensifying — ~95% of Massachusetts is now in moderate drought (D1) after early-July heat waves. UMass's next message is July 24.

Dx

Diagnose · Active Now

•

Fall webworm small webs appearing on branch tips (tupelo and others); Japanese, Oriental & Asiatic garden beetles all active.

•

Cottony camellia & lecanium scale crawlers on holly and magnolia; heavy honeydew and sooty mold.

•

Spotted lanternfly nymphs (2nd–3rd instar) maturing toward the red 4th instar on tree-of-heaven and grape.

•

Box tree moth 2nd-generation larvae feeding on boxwood in Barnstable & Norfolk Co., MA.

•

Oak & two-spotted spider mites rising in the heat; cedar-apple rust and beech leaf disease visible.

℞

Prescribe · Timing & Materials

•

Fall webworm: prune out and destroy small nests now; Btk / spinosad on young larvae inside opened webs.

•

Cottony / lecanium scale: hose off with a strong jet; time horticultural oil to crawler emergence (tape-trap the trunk to monitor).

•

Box tree moth: Btk, spinosad, or chlorantraniliprole; report finds to MDAR.

•

Mites & drought: rinse dust, use a selective miticide only if damaging, and deep-water high-value trees; defer pruning to avoid drawing borers.

MA

Mid-Atlantic & DMV

NY · NJ · PA · MD · DE · DC · VA · WV

GDD · Accumulated

~1,700–2,200

0

1,500

3,000+

Conditions: Warm and humid with periodic heavy rain — strong foliar-disease pressure. SLF is heaviest in Baltimore City and the central counties (Howard, Baltimore, PG, Montgomery, Carroll, Frederick, Washington).

Dx

Diagnose · Active Now

•

Spotted lanternfly late nymphs molting to the red 4th instar and first winged adults across central MD; heavy honeydew.

•

Fall webworm nests forming on branch tips; Japanese beetle continuing on roses and lindens.

•

Bagworm larvae now larger and harder to kill; crapemyrtle bark scale + aphid honeydew and sooty mold.

•

Azalea & sycamore lace bug 2nd-generation stippling; gloomy scale on red maple.

•

Spider mites and ambrosia beetles on heat- and drought-stressed stems.

℞

Prescribe · Timing & Materials

•

Spotted lanternfly: scout and report new counties; hose saplings, band tree-of-heaven, and use neem or pyrethrum only if populations overwhelm. Adults feed mainly on woody trees.

•

Fall webworm: prune and destroy small webs; Btk on young larvae.

•

Bagworm: larvae are past the low-tox window — step up to chlorantraniliprole (Acelepryn / Mainspring).

•

Crapemyrtle bark scale: systemic imidacloprid / dinotefuran drench with pollinator caution, IGR at crawlers, dormant oil later.

•

Lace bugs: hort oil / insecticidal soap to leaf undersides on nymphs; systemic if heavy.

SE

Southeast

NC · SC · GA · TN · AL · MS · FL · VA

GDD · Accumulated

~2,400–3,400

0

1,500

3,000+

Conditions: Hot and humid; the season's furthest along, with a high honeydew and sooty-mold load. Sap-feeders and foliar disease dominate the week.

Dx

Diagnose · Active Now

•

Crapemyrtle bark scale (all stages) + crape myrtle aphid driving heavy sooty mold; Japanese beetle waning.

•

Lace bugs (azalea, sycamore) stippling; gloomy & obscure scale on maple and oak.

•

Fall webworm nests on sourwood, pecan and many hosts; orange-striped oakworm beginning as summer advances.

•

Southern pine beetle & ambrosia beetles on stressed pines and hardwoods; southern red spider mite in the heat.

•

Cercospora leaf spot & powdery mildew on crape myrtle.

℞

Prescribe · Timing & Materials

•

Crapemyrtle bark scale: systemic imidacloprid / dinotefuran drench before bloom with pollinator caution, IGR at crawlers, dormant hort oil; wash off sooty mold.

•

Lace bugs: hort oil / insecticidal soap on nymphs (leaf undersides); systemic if heavy.

•

Crape myrtle disease: resistant cultivars, airflow, labeled myclobutanil / propiconazole / thiophanate-methyl.

•

Fall webworm: prune small nests; Btk on young larvae.

•

Pine & ambrosia borers: stress reduction and sanitation; do not move infested wood.

MW

Midwest & Great Lakes

OH · MI · IN · IL · WI · MN · IA · MO

GDD · Accumulated

~1,500–2,100

0

1,500

3,000+

Conditions: Development is running ~2 weeks early. Iowa State reports Japanese beetle edge-feeding increasing; pockets are dry (mite pressure) while others stay wet. Use MSU Enviroweather / GDDTracker for local timing.

Dx

Diagnose · Active Now

•

Japanese beetle at peak — heavy edge-feeding on roses, lindens and grapes.

•

Emerald ash borer adult flight across the Great Lakes; ash decline and epicormic sprouting.

•

Fall webworm nests beginning; bagworm feeding in the southern Midwest.

•

Spider mites flaring in dry pockets; magnolia scale crawlers approach in August.

•

Oak wilt risk — warm-season oak wounds invite sap-beetle vectoring.

℞

Prescribe · Timing & Materials

•

Japanese beetle: tolerate light feeding or handpick on specimens; chlorantraniliprole / imidacloprid where thresholds warrant (mind bloom), or carbaryl / permethrin on small trees. Keep lure traps away from valued plants; skip turf irrigation July–mid-August to discourage egg-laying.

•

EAB: systemic trunk injection (emamectin benzoate) for high-value ash on cycle.

•

Oak wilt: do not prune oaks now; paint any unavoidable wounds immediately.

•

Fall webworm / bagworm: prune webworm nests; step bagworm up to chlorantraniliprole as larvae enlarge.

W

West & Pacific

CA · OR · WA · NV · AZ · CO · UT · ID · MT

GDD · Accumulated

Highly variable

Coast / high elev.

—

Inland / low desert

Conditions: Wide range by elevation and coast vs. inland; irrigation-driven stress is the key variable and fire season is underway across much of the interior West.

Dx

Diagnose · Active Now

•

Borers on drought-stressed trees — invasive shothole borer, Mediterranean oak borer, and goldspotted oak borer active in CA.

•

Emerald ash borer expanding in Oregon's Willamette Valley (Silverton, Tualatin, near Newberg; five counties quarantined; peak adult flight hit end of June).

•

Aphids with honeydew and sooty mold; spider mites flaring in heat and road dust.

•

Bacterial blast / blight / canker on apple, citrus and stone fruit; yellowjackets building.

℞

Prescribe · Timing & Materials

•

Borers: deep-water summer-rainfall-adapted trees, avoid fresh wounds, and don't move firewood; in EAB zones, inventory ash and consider systemic protection, then report.

•

Aphids: strong water spray, conserve natural enemies, tolerate on established plants.

•

Stone-fruit canker/blight: prune out in dry weather, cutting several inches into healthy wood.

•

Mites: rinse dust, use hort oil or a selective miticide only if damaging; protect predators.

•

Fire: maintain defensible space and thin fuel ladders around trees and structures.

Field notes — read before you spray

Catch webworm early. Nests are far easier to prune out now than in three weeks. Scout the south side of crowns first, where webs appear first.

Heat is a mite multiplier. Dust and drought accelerate spider mites — hose down dusty canopies and reserve miticides for real damage to protect predators.

GDD is a compass, not a clock. Figures are base 50°F from Jan 1 and approximate. Pull your local station (NEWA, MSU Enviroweather, or your state tool) before timing an application.

Sources · Cooperative Extension & USDA

Compiled from public reporting by land-grant cooperative extension services and USDA partners, including UMass Extension Landscape Message (July 10, 2026); University of Maryland Extension IPMnet & Maryland Dept. of Agriculture; Rutgers Plant & Pest Advisory; NC State Extension & Clemson HGIC; Michigan State University Extension & Enviroweather; Iowa State ICM & UW-Madison; UC Statewide IPM Program; Oregon Dept. of Forestry Tree Health Threats Bulletin (July 2026); and USDA NIFA / USDA Forest Service cooperative forest-health programs. Regional summaries are paraphrased; consult the original bulletins and your local extension office for specifics.

Manage fall webworm, mites, and SLF with region-specific pest control advice.

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