🦗 Wildlife Guides

Katydid Eggs: What Those Neat Rows on Your Twigs Really Are

You were pruning, or raking, or just looking closely at a shrub — and you found a line of flat gray discs glued to a branch in a pattern too tidy to be an accident. Here's what laid them, and why the answer is don't spray.

What are katydid eggs? Katydid eggs are flat, oval, seed-like discs about an eighth of an inch long, laid in overlapping double rows along a twig so they resemble a line of fish scales or a row of tiny gray lentils. They're laid in late summer and fall, they overwinter on the branch, and they hatch the following spring. They are completely harmless and require no treatment.

Almost everyone who searches for this found something first and is now trying to figure out whether they have a problem. Short version: you don't. What you found is one of the tidiest pieces of engineering in a Michigan woodlot, and the correct response is to put the twig back where you found it.

How the eggs are arranged

Greater angle-wing katydid eggs form a long, low "tent" of two overlapping rows running straight down a twig.

What katydid eggs look like

The eggs of the greater angle-wing katydid — the big leaf-mimicking species that's most likely responsible for what you found — run about an eighth of an inch to just over that, roughly 3 to 4 millimeters. They're flattened ovals, closer to a lentil or a sunflower seed than anything you'd picture as an egg.

They start out dark, nearly black, when freshly laid, and turn gray or cream within a short time. The arrangement is the real tell: two rows, overlapping, each egg tucked partly under the one ahead of it, forming a continuous low ridge that runs along the twig like a miniature roofline. Descriptions across a century of extension literature keep landing on the same comparison — fish scales.

Not every katydid does it this way. The fork-tailed bush katydid, which is abundant in Michigan shrubs and gardens, inserts its eggs directly into the edge of a leaf instead. Those show up as small oval swellings along the leaf margin, and people usually mistake them for a leaf disease rather than an insect.

Katydid eggs vs. scale insects

This is the confusion that actually costs people money, because scale insects genuinely do damage plants and genuinely are treated with dormant oil. Katydid eggs are not scale, and the difference is easy to see once you know what separates them.

	Katydid eggs	Scale insects
Spacing	Uniform, deliberate, evenly overlapping	Irregular, clustered, random
Surface	Smooth, flat, hard	Bumpy, waxy, sometimes cottony
Shape	Flattened ovals, all identical	Domed or lumpy, varying sizes
Pattern	A single straight line down the twig	Scattered patches, often at joints
Plant damage	None	Sticky honeydew, yellowing, dieback

The one-sentence version: if it looks like something measured it out, it's katydid eggs. Scale insects don't do geometry.

Where you'll find them

Twigs and small branches of shrubs and young trees are the standard location, and the female isn't casual about site selection. She roughens the bark first, then glues each egg down individually. That's why they don't wash off in rain and why scraping them takes real effort.

But they turn up in stranger places, and this is where most people encounter them for the first time:

🔍 Places people find katydid eggs

Window screens. The mesh gives the ovipositor something to grip, and a female will work a row right into the screen fabric. This is the single most common "what is infesting my house" version of the question.

Clothesline wire and fence wire. Same logic — a thin horizontal surface she can straddle.

Garden shrub stems. Butterfly bush, lilac, rose, and fruit tree twigs are all common. Prune in winter and you'll find them.

Leaf edges. Bush katydid eggs, embedded in the margin, usually mistaken for a fungal problem.

Should you scrape them off?

No. And it's worth being specific about why, because the reflex to remove anything unfamiliar from a plant is strong.

Katydids are light feeders. They nibble small amounts across a lot of different plants rather than concentrating damage on any one, and their populations stay naturally sparse because so many things eat them — birds, bats, frogs, snakes, spiders, and predatory wasps. In a home landscape they simply never reach the numbers that would cause noticeable harm. Extension services across the country reach the same conclusion: no control measures recommended.

What you'd actually accomplish by scraping is removing food from the animals that depend on them. On our own 30 acres, a single generation of katydids feeds screech owls, bats, nighthawks, shrews, and every foliage-hunting songbird that comes through. There's also a specialist — the great black wasp hunts angle-wing katydids specifically, and it's an outstanding pollinator that has nothing to provision its burrow with if the katydids are gone.

If you already cut the twig off, the fix is simple: put it back outside, in a sheltered spot at the base of a shrub. The eggs need to experience winter cold to break dormancy. Keep them warm indoors and they'll hatch early into a house with nothing to eat.

The timeline, start to finish

The greater angle-wing runs one generation a year in Michigan, and the whole calendar is built around a single hard constraint: the egg is the only stage that survives winter.

Late summer into fall — adults mate and females lay. This is happening right now on our property, through September and into October depending on how the cold arrives.

First hard freeze — every adult dies. The nightly chorus that's been building since late July stops entirely, and the woods go quiet.

Winter — the eggs sit on bare twigs through everything a Michigan winter delivers, in diapause, waiting on accumulated cold and then warmth.

Spring — nymphs hatch out looking like miniature wingless adults with comically oversized antennae, and start feeding on new growth.

Mid to late summer — after several molts they reach adulthood, grow wings, and the males begin calling. Total lifespan is about a year, with only the last few weeks spent as the insect anybody recognizes.

Why the eggs cost so much

Here's the detail that makes this whole thing more interesting than a pest-control question. When a katydid pair mates, the male doesn't just transfer sperm — he hands over a spermatophore, a large nutritive package that the female eats and metabolizes directly into her developing eggs.

That's a real measure of how expensive egg production is for a two-inch insect living on leaves. Foliage is a poor source of the protein and minerals a clutch demands, and the male's contribution helps close the gap. It also suggests why a gravid female might do something out of character to find more.

We filmed one on the ground doing exactly that — walking a dead stick on bare soil, well below the canopy where the species belongs, reaching down and eating something off the dirt. The full katydid guide has that video, along with the identification breakdown for every species you're likely to meet in Michigan →

Frequently Asked Questions

What do katydid eggs look like?

Katydid eggs are flat, oval discs about an eighth of an inch long — closer to a lentil or sunflower seed in shape than a typical egg. Greater angle-wing katydids lay them in two overlapping rows along a twig, each egg tucked partly beneath the one ahead of it, so the row resembles a line of fish scales or a miniature roofline. They start out nearly black and turn gray or cream shortly after being laid.

When do katydid eggs hatch?

In spring, usually April into May in the Great Lakes region, after the eggs have overwintered on the twig where they were laid the previous late summer or fall. The egg is the only life stage that survives winter — every adult katydid dies at the first hard freeze. Eggs kept warm indoors will hatch early, sometimes within days, because the warmth accelerates development.

Should I remove katydid eggs from my plants?

No. Katydids are light feeders whose populations stay naturally sparse, and they don't reach numbers that cause meaningful damage in a home landscape. Extension services generally recommend no control measures at all. Removing the eggs takes food away from the owls, bats, birds, and predatory wasps that depend on katydids. If you've already cut the twig off, set it back outside in a sheltered spot.

Are these katydid eggs or scale insects?

Check the spacing and the surface. Katydid eggs are smooth, flat, identically sized, and spaced with obvious regularity in a single line down the twig. Scale insects are lumpy or waxy, vary in size, and cluster irregularly in patches. Scale also produces sticky honeydew and causes yellowing or dieback; katydid eggs cause no plant damage whatsoever.

Why are there katydid eggs on my window screen?

The mesh gives the female's ovipositor something to grip, so she can insert and glue a row of eggs into the screen fabric the same way she would onto roughened bark. It's not a sign of an infestation and the eggs won't hatch inside the house — nymphs that emerge will disperse outward looking for foliage. You can leave them or gently transfer them to a shrub outside.

How many eggs does a katydid lay?

A single female greater angle-wing lays her eggs in multiple batches across late summer and fall, typically a dozen or more per row and often several rows on different twigs. Total output per female runs into the dozens to over a hundred depending on her condition and how long she survives before the first freeze.

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