Every Other Beneficial We Sell Is Farmed. Ladybugs Are Caught.

Predatory mites are farmed. So are beneficial nematodes, both kinds of green lacewing, all three Aphidius wasps, the predatory midge, the mealybug destroyer and the rove beetle. They are produced in insectaries, on purpose, in controlled conditions, by people whose job is to produce them.

Ladybugs are collected off a mountain with a vacuum.

University of California's wording is that commercially available Hippodamia are “field collected from their overwintering sites using portable vacuum devices” — aggregations in the Sierra Nevada and the California foothills, where the beetles spend the cold months packed together in their thousands. That is the whole supply chain. There is no insectary.

This one difference explains most of what is peculiar about ladybugs as a product: why they are cheap per predator, why they leave within a day or two, why outcomes vary more than they do with a sachet — and why what arrives sometimes has company.

What “caught” actually means

A convergent lady beetle spends the winter in a cluster. Not a few dozen — aggregations run to enormous numbers in sheltered spots at altitude, and they have done for as long as anyone has looked. Collectors go to those sites and vacuum beetles into containers. The beetles are chilled, packed, and shipped, and the commercial lots run from about 1,500 up to 72,000 adults.

The consequence that is easy to see is price — nobody had to feed these animals for a generation, so a ladybug costs a fraction of what a reared predator costs. What arrives is also an adult out of a winter cluster rather than a young beetle off a diet, which is why the handling instructions are the ones they are: refrigerate, never freeze, and warm and feed it if you are holding it for a week.

Being caught does not explain why they fly away. Worth saying plainly, because the two facts sit next to each other and get welded together. Rearing does not change an insect's dispersal behavior; a reared convergent lady beetle would be the same species with the same programming. The departure is real, measured, and unexplained, and it is a different subject from this one.

The consequence that is the subject of this article is the third one. An insectary colony is a closed system that somebody inspects. A wild aggregation is not, and what you receive is whatever was in the cluster.

The passengers

Two are documented well enough to name.

Tubulinosema hippodamiae

A microsporidium — a spore-forming intracellular parasite, the same broad group as the pathogens that trouble honeybees and silkworms. It was described in 2011 from convergent lady beetles received from commercial insectaries, and the describing authors' own sentence about frequency is the most useful one in this article:

It is not new and it is not a modern contamination story. The pathogen it most resembles is Nosema hippodamiae, reported from this beetle by Lipa and Steinhaus in 1959. People have been finding things inside collected lady beetles for the better part of a century.

Dinocampus coccinellae

A braconid wasp that lays inside an adult lady beetle. The larva develops in the beetle, emerges, and spins a cocoon under it. It is a native North American parasitoid and it turns up in wild-caught beetles because it is part of wild lady beetle life.

Why it lands on the part you were buying

Here is where this stops being trivia. The durable half of a ladybug release is not the beetles, it is the eggs they lay before they go — the larvae that hatch cannot fly and stay on the plant for about two weeks.

The 2011 description traced where the spores sit in the beetle: the fat body, the Malpighian tubules, the pyloric valve epithelium, the ventral nerve cord ganglia, the muscles — and the ovaries.

Which is why the transmission figures read the way they do. Across every lady beetle species examined in a 90-day trial, 100 percent vertical transmission was eventually observed: infected mothers hand it to their eggs. And in the convergent lady beetle specifically, infection has a measured cost to exactly the thing you were hoping for:

Roughly forty percent fewer eggs, and about twelve days less life. A second study, over 90 days, found the same direction — fewer eggs, shorter life — in H. convergens, and did not find those effects in the three other lady beetle species it tested. So the fecundity cost appears to be specific to the host this pathogen came from, which is also the host in the tub.

It moves, including into a lacewing

Two findings here, and the qualifier on the first one matters.

To other lady beetles, in a laboratory

The microsporidium was transmitted horizontally to three other coccinellids — the two-spotted lady beetle Adalia bipunctata, the seven-spot Coccinella septempunctata, and the multicolored Asian lady beetle Harmonia axyridis. Under laboratory conditions. That phrase is in the paper and it belongs in any sentence that repeats the finding: this is a demonstration of what the pathogen can do, not a measurement of what happens in a garden.

Spore counts in the infected two-spotted lady beetle did not differ from those in H. convergens, which makes the native two-spotted an equally suitable host — while infection was lighter in the two introduced species. If you have read our piece on native versus invasive ladybugs, that is an uncomfortable direction for the result to point, and it is the result.

To a green lacewing, without infecting it

This is the strangest finding in the set. Researchers offered infected and uninfected lady beetle eggs to green lacewing larvae — a realistic thing to happen, since a lacewing larva will eat an egg it finds. Larvae that ate two or more T. hippodamiae-infected eggs took almost three days longer to develop.

And at the end of the trial, none of them were infected. The authors'own reading is that the pathogen “influenced lacewing larval development without establishing an infection.” Something in an infected egg slows a lacewing down without taking up residence in it.

Three days matters for a lacewing, for a reason the paper names and our own lacewing pages already warn about. A larva that is still a larva for longer “remain[s] vulnerable to cannibalization by sibling larvae or other predators.” Lacewing larvae cannibalize, so a slower larva is a larva that gets eaten.

The wasp

Dinocampus coccinellae gets its own paragraph because of one number. When the wasp develops inside an infected beetle, every one of its offspring picked up the pathogen — all 48 in the trial. The wasps' development time was unaffected, but infected wasps produced significantly fewer offspring, and the infection was found throughout their tissues except the ovary.

So a beetle's passenger reaches its parasitoid's next generation. That is not a consumer problem; it is a nice illustration of why a wild-caught animal is a package rather than an item.

The case for not overreacting

Everything above is real and some of it sounds worse than the evidence supports. The same research group, summarizing its own decade of work in a 2023 thesis, puts the two lady beetle microsporidia like this: they “delay larval development but have no other observable effect on the host” — under optimal laboratory conditions.

That is a more modest statement than the fecundity table above, and both come out of the same laboratory. Reading only the alarming half would be picking. So here is the whole shape of it:

• Consistent across every study: infection delays larval development.
• Consistent: larval mortality is not affected. Infected larvae are not dying.
• Consistent: sex ratios are not affected, and come out about 1:1.
• Found in H. convergens, not in the other species tested: fewer eggs per female, and a shorter adult life.
• Stress made it worse in one species and not in ours: an irregular food supply interacted with infection in the two-spotted lady beetle, and that interaction was not observed in infected H. convergens.

A microsporidium is a chronic, debilitating pathogen rather than a lethal one. Nothing here describes a tube of dying beetles, and nothing here is a reason to be afraid of the animal.

What is not published

What share of a shipment is infected. That is the number any buyer would ask for, and we could not find it published anywhere we could open. The word from the lab that described the pathogen is “occasionally,” and that is where this article stops.

Also not established, and worth saying because it is the obvious next question: whether any of the laboratory transmission results translate to a release in a garden. The horizontal transmission work was explicitly laboratory work. Nobody has followed a bought tub into a back yard and counted what happened to the local lady beetles.

What to actually do with this

Nothing, if you are buying ladybugs for the job they are good at. That is the real conclusion and it is not a hedge.

A ladybug release is a burst: about a hundred aphids a day per beetle for the day or two before most of them leave, plus whatever gets laid. Bought at a real rate it is the cheapest large knock-down available, and everything above is priced into a product that already costs a fraction of a reared predator.

Where it should change your decision is when the outcome has to be predictable — a crop you cannot afford to lose, a greenhouse on a schedule, a problem that has to be closed rather than dented. For that, buy something farmed: lacewing larvae, an Aphidius wasp or the predatory midge, produced under inspection, with a known composition.

That is the honest trade, and it is the one the evidence actually supports: wild-caught for cheap volume, reared for a known result.

Common questions

Are the ladybugs sold for release wild-caught?

Yes. Convergent lady beetles sold in North America are field-collected from wild overwintering aggregations in California, using portable vacuum devices, and shipped in lots of roughly 1,500 to 72,000 adults. Unlike predatory mites, nematodes, lacewings or Aphidius wasps, they are not reared in an insectary.

Do store-bought ladybugs carry diseases?

Some carry a microsporidian pathogen called Tubulinosema hippodamiae. The researchers who described it write that beetles received from commercial insectaries are “occasionally” infected, and no published figure for what share of a shipment that means could be found. Infection delays larval development; in this species it also reduces egg production and adult lifespan. It does not increase larval mortality.

Can I tell if my ladybugs are infected?

No. Detection in the published work is done by light microscopy of smear preparations, not by looking at the beetle. A sluggish clustered tub is almost always cold rather than sick, and warming it is the fix.

Is this dangerous to my plants, my pets or me?

No. Microsporidia in this group are pathogens of insects. The concern in the literature is entirely about the beetles' own fitness and about transmission to other beneficial insects.

Could released ladybugs pass this to wild ladybugs in my area?

It has been demonstrated in a laboratory, transmitted to three other lady beetle species including the native two-spotted lady beetle, which proved as suitable a host as the convergent. Whether that happens after a garden release has not been measured by anyone, and that gap is worth being honest about rather than filling in either direction.

Does this affect green lacewings, since I release both?

In one study, yes, and in an odd way. Lacewing larvae that ate two or more infected lady beetle eggs took almost three days longer to develop, and none of them ended up infected. Slower development matters because a larva that stays a larva longer is more likely to be cannibalized by its siblings.

Should I stop buying ladybugs?

No, and that is not where the evidence points. A ladybug release is a cheap, large, short knock-down and all of this is already priced into it. Buy it for that. When the result has to be predictable, buy an insectary-reared organism instead.