What Do Yellow Jackets Eat? Why They Crash Your NH BBQ and How to Stop It
TL;DR
Yellow jackets eat two very different diets across the New Hampshire season: in spring and summer (April through mid-July), workers hunt insect protein — caterpillars, flies, spiders — to feed larvae. In late summer and fall (late July through first frost), with the brood gone, they switch to scavenging sugars — fallen orchard apples, soda, beer, BBQ drippings, maple sap residue, garbage. That protein-to-sugar shift is exactly why yellow jackets crash NH lake-house barbecues in August. Reducing food sources and sealing trash is the front line of prevention.
Diet shift
Protein → Sugar
by late July in NH
Forage radius
~1,000 ft
V. germanica up to ¾ mile (UMD)
Peak scavenging
Mid-Aug – mid-Oct
southern NH window
Protein phase
Apr – mid-July
caterpillars, flies, spiders
Why Yellow Jackets Are Suddenly All Over Your Soda in August
Walk into a Manchester backyard in mid-August and you may meet a wasp on your soda can within minutes. That same yard was wasp-free in June. The reason is biology, not bad luck: a yellow jacket colony spends April through mid-July in protein mode, hunting caterpillars, flies, beetle grubs, leafhoppers, and spiders to feed thousands of growing larvae. Each larva, in exchange for that protein, secretes a sugary droplet that feeds the adult workers — a process called trophallaxis. The workers depend on it for their daily energy.
In late July through August, the queen stops laying brood. Larvae mature, pupate, and emerge — and the steady stream of sugary trophallactic droplets vanishes. Suddenly thousands of adult workers need to find sugar somewhere else. That somewhere is your soda, your Bedford apple drop, your maple sugar shack, your lake-house BBQ at Sunapee, and the trash cans at Bear Brook State Park. Every late-summer scavenging behavior the public associates with 'yellow jacket aggression' is actually starving adults looking for the sugar their larvae used to provide. The mechanism — not the wasp's personality — is what's seasonal.
Southern NH's Yellow Jacket Food Landscape
New Hampshire's late-summer landscape concentrates yellow jacket attractants in ways that other regions don't. The Londonderry / Bedford apple country (sometimes called the 'Apple Way') leaves fermenting fallen fruit in orchards and home yards from August through October — a powerful sugar magnet. NH maple sugar shacks store sap residue and sweet boil-off through summer if operations are not sealed. Bear Brook State Park (Allenstown) and Pawtuckaway State Park (Nottingham) campsites concentrate open trash in mid-August through Labor Day, drawing foragers from ground nests within ~1,000 ft. Lake-house BBQs at Winnipesaukee, Sunapee, and Squam are the canonical NH yellow jacket complaint — and the timing (mid-August through mid-September) lines up almost perfectly with the trophallaxis-loss window. Cottonwoods and elms along the Manchester river corridor and older Concord neighborhoods produce aphid honeydew that yellow jackets harvest as a secondary sugar source.
Species present in NH
- Eastern yellowjacket (Vespula maculifrons)
- German yellowjacket (Vespula germanica)
- Bald-faced hornet (Dolichovespula maculata)
- Aerial yellowjacket (Dolichovespula arenaria)
Peak activity
Late July through first hard frost (Manchester ~Oct 19 NOAA)
Service area
First-frost anchor: Manchester first hard frost ~Oct 19 (50%) / ~Oct 29 (80%) per NOAA 1991–2020 normals — colony food behavior ends within ~1 week of frost
Per UNH Extension's Alan Eaton (writing in Old Farmer's Almanac), the late-summer scavenging behavior tracks the colony's loss of trophallactic sugar reward when brood production ends — not random aggression.
How to identify a yellowjacket
Yellow jacket diet behavior is driven mainly by mouth parts and antennae — workers use sensitive antennae to detect sugar and protein volatiles from a distance, and use chewing mandibles to process both insect prey and soft fruit pulp.
- 01
Antennae
Long, jointed, dark-tipped — yellow jackets use them to detect sugar plumes (fermenting fruit, soda) and protein cues (meat, dead insects) from yards away. This is why a single open soda can recruits multiple wasps within minutes.
- 02
Mandibles
Strong chewing mouthparts that can shred caterpillar tissue, chew fruit pulp, and even chew through interior drywall when V. germanica colonies are sealed into wall voids (Penn State Extension warning).
- 03
Crop (honey stomach)
Workers carry liquid sugar — nectar, fruit juice, soda — in a crop separate from their digestive stomach. This lets them ferry sugar back to the nest as well as drink for energy en route.
- 04
Sting apparatus
Smooth and barbless. Yellow jackets can sting repeatedly while scavenging; this is why disturbing a wasp on a soda can or BBQ plate can lead to multiple stings rather than one.
- 05
Body coloration
Yellow and black bands (V. maculifrons with anchor-shaped marks; V. germanica with diamonds and side spots) signal warning to predators — a classic aposematic display.
Yellowjacket species in New Hampshire
Prevalence based on UNH Cooperative Extension survey data.
| Species | Size | NH status | Prevalence | Typical nest |
|---|---|---|---|---|
Eastern yellowjacket Vespula maculifrons | 12–13 worker mm | native | HIGH | Ground burrows, stone-wall bases |
German yellowjacket Vespula germanica | 12–13 worker mm | invasive | HIGH | Wall voids, attics |
Bald-faced hornet Dolichovespula maculata | 15–18 worker mm | native | MEDIUM | Aerial paper envelope, 5–60 ft up |
Aerial yellowjacket Dolichovespula arenaria | 10–14 worker mm | native | MEDIUM | Aerial nests in shrubs and eaves |
Lifecycle, phenology, and overwintering in New Hampshire
The yellow jacket diet shift is fundamentally a lifecycle problem — protein-foraging is for larvae, and when larvae stop being produced, the workers' personal sugar source vanishes.
Founding queen forages alone
April – early June (NH)
The lone queen drinks early-spring nectar (willow catkin, dandelion) and hunts small soft-bodied insects to feed her first 20–40 larvae.
Worker brood — protein phase
Mid-June – mid-July (NH)
Workers handle all foraging. Diet is predominantly insect protein for larvae; adult workers live on the sugary droplets larvae secrete in exchange (trophallaxis).
Brood peak
Late July (NH)
Larval rearing peaks. Protein demand is at maximum. Sugar foraging is still rare because larvae provide trophallactic sugar.
Trophallaxis collapse
Late July – mid-August (NH)
Queen reduces egg laying; larvae mature and pupate. Trophallactic sugar reward to adults ends. Workers must now scavenge external sugar — the famous BBQ-crashing behavior begins.
Sugar phase + collapse
Mid-August – first frost ~Oct 19 Manchester (NH)
Workers scavenge fruit, soda, sap, garbage. New reproductive queens mate and disperse to hibernacula. At first hard frost, every colony member except mated new queens dies within a week.
12-month NH phenology
12-month diet calendar for southern NH — anchored to Manchester frost normals.
Jan
dormant
No foraging — queens in diapause.
Feb
dormant
No foraging.
Mar
low
Late-month: occasional early queen stir in heated voids; no significant foraging.
Apr
building
Queens emerge late month. Forage willow catkin, dandelion nectar.
May
building
Queen-only protein foraging (small caterpillars, flies) for first larvae.
Jun
building
First workers eclose mid-month — full protein foraging mode begins.
Jul
peak
Heavy protein foraging continues; trophallaxis sugar reward maintains worker energy. Sugar scavenging still rare.
Aug
peak
Brood production ends. Trophallaxis collapse. Sugar scavenging begins explosively — first NH BBQ encounters.
Sep
peak
Peak sugar scavenging — apple drops, late-season fruit, NH state-park trash, lake-house cookouts.
Oct
declining
Manchester first hard frost ~Oct 19 — foraging activity collapses within a week.
Nov
dormant
Workers dead; only mated queens remain (in diapause).
Dec
dormant
No foraging.
Spring / Summer
Live insect protein — caterpillars, flies, beetle grubs, leafhoppers, spiders. Workers chew prey into paste and feed it to larvae. Adults survive on trophallactic sugar droplets secreted by larvae in exchange.
Late summer / Fall
Sugar scavenging — fallen orchard apples (Londonderry / Bedford), plums and peaches, soda, beer, wine, hummingbird feeders, BBQ drippings, maple sap residue, aphid honeydew on cottonwoods and elms, garbage residue at state-park campsites.
NH overwintering
Yellow jackets do not eat or forage during NH winter — only mated queens survive, and they enter diapause without feeding.
- Stone walls — iconic NH overwintering habitat
- Cedar shingles and clapboard gaps on older Manchester, Concord, and Portsmouth housing
- Attic insulation
- Woodpiles stacked against south-facing walls
NH activity calendar
Frequently asked
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