How Long Do Aphid Eggs Take to Hatch? Timing by Species

How long do aphid eggs take to hatch? The extension guides we checked give no fixed count of days. Eggs laid in autumn stay on the host plant through winter and hatch in spring, so the wait is usually months, and warmth and bud growth set the date. For one species there is a hard number: Iowa State University Extension says soybean aphid eggs begin hatching at 147 to 154 growing degree days (GDD) counted from January 1.

This page gives the hatch cue for four crop aphids, the speed of each stage after hatch, and a calculator that estimates days left to hatch from your own weather numbers.

How long do aphid eggs take to hatch, by species

The Royal Horticultural Society says most aphid species overwinter as eggs, although some stay active in mild winters or on indoor plants. The egg is the hardy stage. It carries the species through cold weather and the time when deciduous hosts have no leaves. That is why a calendar day count tells you little. The guides cited here describe hatch by a plant stage or a heat total, not by days since laying.

The sources for the table are RHS on rosy apple aphid, UC IPM on black cherry aphid and UC IPM on leaf curl plum aphid. The March date belongs to California. A colder district will run on its own clock, so watch the buds instead of the date.

The timing also explains the fall flight. University of Wisconsin-Madison Extension says that shorter days in late summer trigger the mating forms that lay fertilized eggs, and that those eggs survive adverse winter conditions.

What the eggs look like

UC IPM describes both rosy apple and black cherry aphid eggs as shiny and black. Rosy apple eggs are also elongated. Look for them on spurs, shoots and twigs during dormancy, using a hand lens. In leaf curl plum aphid, UC IPM uses orchard history as the best guide to populations and advises sampling during dormancy when aphids are not a chronic problem.

Crops where you will never find eggs

Do not search the crop itself for every species. Iowa State notes that soybean aphid eggs are not found in soybean at all. They sit on buckthorn, and winged females reach the crop in early June after two or three generations on that shrub.

Some populations skip eggs altogether. Cesar Australia reports that invasive Russian wheat aphid in Australia reproduces asexually, with females giving birth to live female young. In those systems the egg question does not apply, and the first sign is the winged or wingless aphid in the crop. The same is true of the summer phase of egg-laying species. UC IPM says that in California’s mild climate most aphids reproduce this way for most or all of the year, with females often producing as many as 12 live young a day without mating.

▶ Scouting and control strategies for soybean aphid. · 22:28

Using heat units to predict aphid egg hatch

A growing degree day measures heat above a base temperature. Iowa State gives soybean aphid a lower development threshold of 50°F and an upper threshold of 95°F. A day with an average of 60°F adds about 10 GDD. A day averaging 48°F adds none. Add those values from January 1 and compare the total with the hatch range.

The plant gives a second check. Iowa State says the start of hatch coincides with buckthorn bud swell, which it puts slightly later, at 165 to 171 GDD. If you have buckthorn near your fields, swelling buds mean hatch has likely begun. The chart shows how close the two windows sit.

Published GDD figures for hatch are species-specific. Do not apply the soybean aphid range to apple, cherry, plum or cereal aphids. For those, use the plant-stage cue in the table above.

Chart

Soybean aphid hatch and buckthorn bud swell

Growing degree days from January 1, base 50°F

Calculate days left until egg hatch

Enter your own weather values below. The tool uses the simple average method: the day’s high plus low, divided by two, minus the base temperature. Your state pest map may use a different method, so treat the answer as a date to begin looking, not a forecast.

Try the numbers for your own farm below.

Aphid life cycle after the eggs hatch

Hatching is the slow part. Everything after it moves fast.

1. Egg. Laid in fall or winter by sexual forms, in some cases on an alternate host that is usually a perennial, according to UC IPM.
2. Nymph. Young aphids look like small adults. They molt about four times. There is no pupal stage, and despite the common search term, aphids have no larvae.
3. Wingless adult. In warm weather, many species go from newborn nymph to reproducing adult in seven to eight days (UC IPM). Each adult can produce up to 80 young in about a week.
4. Winged adult. Overcrowding, an ageing host or a change of season triggers wings, says the RHS. These adults carry the colony to a new plant.
5. Fall return. In host-alternating species, winged forms fly back to the winter host. Mating and egg laying restart the cycle.

Rosy apple aphid shows the full pattern. The UC IPM apple guideline says winged forms leave apple in late spring for plantain, then return in fall and lay eggs on spurs and shoots. Our guide to aphids with wings covers that migrating stage.

How fast do aphids reproduce?

Iowa State’s summer figures for soybean aphid are the most detailed here: all offspring are female, each female gives birth to 3 to 8 aphids a day for 30 days, and one generation takes 7 to 10 days. Under good conditions a population can double in 2 to 3 days. Iowa State reports that development is favored at 72 to 77°F with relative humidity below 78%.

Speed differs by species and by weather. Cesar Australia gives about 2 to 3 weeks per generation for green peach aphid at daily highs of 20 to 25°C. This is slower than the warm-weather figures from California and Iowa, so a single number for “aphids” will mislead you.

How long do aphids live?

Iowa State does not state a life span. It gives soybean aphid a generation time of 7 to 10 days and about 30 days of giving birth, in summer. Other species and seasons will differ, and the egg stage adds months for those that overwinter.

Chart

Published time to the next generation

Days, low end of each source’s figure; UC IPM is newborn to reproducing adult; selected species

How temperature changes aphid development

Cold slows aphids sharply. Under laboratory conditions, Cesar Australia reports a Russian wheat aphid generation of about 20 days at 10°C and 9 days at 20°C. Ten degrees of warmth cut the time by more than half.

Chart

Russian wheat aphid generation time by temperature

Approximate days per generation, laboratory conditions

More heat does not always help the pest. Cesar notes that temperatures above 25°C may limit where Russian wheat aphid can live. UC IPM says that many species cause the greatest damage in late spring, when it is warm but not hot. For cereals in southern Australia, Cesar’s oat aphid note says that populations peak in late winter and early spring and that daily highs of 20 to 25°C favor development. The corn aphid note says the same.

A warm spell in early spring can bring a heat-driven hatch forward. It also means your GDD total matters more than last year’s date. Keep your own record of the date of first hatch in each block or shelterbelt. After a few seasons it will give you a local reference.

A spring hatch watch in five steps

1. Name the aphid. Check last season’s records. The species decides the winter host and the hatch cue.
2. Find the winter host. Map orchard blocks with a history of aphids and any buckthorn beside soybean fields.
3. Start counting heat. Track GDD from January 1 if your species has a published range. Otherwise, follow bud stage.
4. Look closely as buds move. Check spurs and young growth every few days during bud swell. UC IPM’s home and landscape note suggests at least twice a week when plants are growing rapidly.
5. Write it down. Record the date of first nymphs, the GDD total and the bud stage. Compare them with next year’s numbers.

Newly hatched rosy apple aphids are dark green and sit on new growth in early spring, according to UC IPM, so tender tips are the place to begin. Once you see nymphs, the next generation may be only a week or two away in warm weather.

When to act: treatment windows around hatch

The egg stage gives orchard growers a real window. For field crops, the decision comes later and rests on counts in the crop. Always check the product label and local rules, and ask a licensed adviser if you are unsure. The US EPA says pesticide labels are legally enforceable, so the label is the legal guide to using a product.

Orchards: dormant and delayed-dormant

• Timing. UC IPM says supreme- or superior-type oils kill overwintering eggs on fruit trees when applied as a delayed-dormant spray, just as eggs begin to hatch in early spring. UC IPM adds that these treatments do not give complete control and are probably not justified for aphids alone.
• Plums. UC IPM’s leaf curl plum aphid guideline names the dormant or delayed-dormant period as the best time to treat, but its advice on oil differs by page. Its home and landscape note prefers oil right after leaf fall in early November. Its orchard guideline says oil is not recommended for a November 1 treatment, and lists oil at green tip or popcorn, when eggs are hatching. Check local advice before you choose.
• Curled leaves. Oil must contact the aphids. Once they shelter in curled leaves, oil alone will not reach them.
• Heat and stress. UC IPM warns against soaps or oils on water-stressed plants or when it is above 90°F.

Field crops: scout, then use thresholds

• Soybean. Iowa State recommends scouting every 7 to 10 days. Its threshold through R5 is an average of at least 250 aphids per plant, at least 80% of plants infested, and numbers rising. It says neonicotinoid seed treatments are not reliable for this pest, because aphids usually arrive after the concentration has faded. It also reports pyrethroid resistance in Iowa, Minnesota, South Dakota and North Dakota.
• Cereals. UC IPM’s California guideline says thresholds for bird cherry-oat aphid are not well established. It advises against considering treatment until numbers exceed 50 to 60 per tiller. It also recommends destroying volunteer cereals before a new crop emerges.
• UK grain and oilseed growers. AHDB describes a suction-trap network that identifies and counts aphids, with counts published weekly. It also warns that some aphids overwinter in crops and may be present before flights begin.

Protect the natural enemies

Lady beetles, lacewings, hoverfly larvae and parasitic wasps all feed on or attack aphids. Look for golden-brown, brown or black mummies, a sign that wasps are at work. Iowa State says natural enemies can be very effective in its fields, and that spraying only when scouting calls for it helps preserve them. Green peach aphid adds another reason for care. Cesar reports resistance to several chemical groups and advises rotating groups and using biological control.

Knowing the winter host also helps you plan scouting. For soybean aphid that means knowing where buckthorn grows. Iowa State ranks early-planted fields and fields with nearby buckthorn stands as the first to scout.

▶ Integrated pest management in peach orchards from spring to summer. · 20:27

Using satellite maps alongside scouting

A satellite cannot see an aphid egg or name a pest. A vegetation map can show a patch that is growing more slowly than the rest of the field. That helps you decide where to walk first. Then you count aphids on the plants and apply the threshold. Farmonaut provides this kind of field map. The cause of any patch still has to be confirmed on the ground.

▶ How to monitor crops with the Farmonaut web app. · 8:43

How we checked these numbers

We used extension services, university pest guides, a horticultural society and crop research organizations, and read each page in November 2026. We removed day counts from the earlier version of this page, including a “3 to 5 day” hatch figure, because none of these guides gives one. Where a figure covers one species or one region, the text says so.

Related pages on our site: agribusiness field team management, fleet management, carbon footprinting, product traceability, crop loan and insurance checks, weather API documentation, satellite API, aphid predator larvae, aphid honeydew, aphids vs mealybugs.

FAQ

How long does it take for aphid eggs to hatch?

Overwintering eggs laid in autumn hatch the next spring, so usually months. The date follows warmth and bud growth. Soybean aphid eggs begin hatching at 147 to 154 GDD from January 1 (Iowa State).

What time of year do aphid eggs hatch?

Spring. The cue differs by aphid: as apple leaves emerge for rosy apple aphid (RHS), shortly before bloom for black cherry aphid, and generally early March in California for leaf curl plum aphid (UC IPM).

Do all aphids lay eggs?

No. UC IPM says most aphids in California’s mild climate give birth to live young for most or all of the year, and invasive Russian wheat aphid in Australia reproduces asexually (Cesar Australia). Most species do overwinter as eggs, says the RHS.

How fast do aphids reproduce after hatching?

In warm weather, many species reach reproducing age in seven to eight days, and each adult can produce up to 80 young in about a week (UC IPM). Soybean aphid numbers can double in 2 to 3 days under good conditions (Iowa State).

Can you kill aphid eggs before they hatch?

On fruit trees, UC IPM says supreme- or superior-type oils kill overwintering eggs when applied just as hatching begins, though control is not complete and UC IPM says the spray is probably not justified for aphids alone. Follow the label and local rules.