Macrocheles robustulus
A soil-dwelling predatory mite sold in Europe as Koppert's Macro-Mite and, in the UK, as Dragonfli's Mighty Mite. Like Stratiolaelaps scimitus, it lives in moist, organic compost and eats fungus gnat eggs, larvae and pupae and thrips pupae there, and it rarely climbs onto the plant. Koppert describes its effect as slow but steady, so it goes in preventively or at the first gnats. No US supplier listing it was found, so in North America the practical choice is Stratiolaelaps.
At a glance
- Mode
- Soil-dwelling generalist predator
- Rate
- 100–500 /m² per release (Koppert)
- Ships as
- 50,000 mites in sphagnum moss
- Temp
- Minimum 59 °F (15 °C)
- Media
- Moist, loose, organic; no standing water
- Availability
- Europe, UK and a few other markets; no US listing found
How it works
Koppert calls it a generalist soil predator: it feeds on the eggs, larvae and pupae of sciarid flies (fungus gnats), on thrips pupae and on other soil-dwelling insects, and it is found in and on the soil and at the base of plant stems. Dragonfli adds springtails and fly maggots to the list of what it has been seen eating. It will very rarely climb onto the plant, so it does not reach the adult flies or the thrips feeding on leaves; Dragonfli pairs it with yellow sticky traps for the adults.
The effect builds slowly. Koppert describes the reduction as slow but steady and advises one or two repeat releases, starting preventively or at the first sign of the pest; Dragonfli suggests adding more if numbers have not fallen after about a week. For thrips it is only a supplement — Koppert says to combine it with a foliar predator such as Amblyseius swirskii or Neoseiulus cucumeris, or with Orius.
Is it established?
A soil predator leaves no mummies or shrivelled prey you can see. Read it on the pest: potato slices for gnat larvae and yellow cards for adults.
- DAY 1Spread the carrier on the compost; the mites work in and on the soil, not on the plant
- DAY 7Dragonfli: if gnat numbers are not falling, add more mites
- WEEKS 2+A slow, steady fall in larvae under potato slices; repeat once or twice (Koppert)
- THROUGHOUTKeep yellow cards up: the mites do not reach adult flies, so trap those (Dragonfli)
Release & handling
Koppert ships 50,000 mites in a cardboard tube of sphagnum moss; Dragonfli uses bottles of vermiculite from 5,000 up. Spread them as soon as they arrive. If you must hold them, one to two days at 50–59 °F (10–15 °C), in the dark, lying on its side.
Use the same day
Storage is one to two days at most (Koppert).
50–59 °F, dark, horizontal
10–15 °C, the tube lying on its side.
Turn, then spread on the media
Turn and shake gently, then spread evenly on the soil or compost around the stem bases. Dragonfli: one 5,000 bottle treats up to 20 m².
Moist, not waterlogged
The medium must be moist, loose and organic. The mites do not tolerate standing water.
Pesticide sensitivity
No published side-effects table for this species was found. Dragonfli advises no natural pyrethrum for two days before release and warns that other insecticides may leave residues harmful to predatory mites for much longer; Koppert points to its side-effects tool. Check a product →
When to choose something else
Outside Europe this is mostly a name to recognise. Reach for something else when:
- You are in the US or Canada — no supplier listing was found; use Stratiolaelaps scimitus (Hypoaspis miles), which is sold for the same job
- Larvae are already damaging cuttings — add a Steinernema feltiae drench, which Dragonfli pairs with it against fungus gnats
- Thrips are on the leaves and flowers — this mite only takes the pupae in the media; add a foliar predator
- The compost is below 59 °F (15 °C) or sits waterlogged — Koppert's minimum, and Dragonfli's warning on standing water
Where to buy
No US or Canadian retail listing was found in September 2026. Suppliers listed alphabetically, not ranked; helpfulbugs takes no commission and does not sell insects.
- Dragonfli (Mighty Mite)5,000 / 10,000 / 25,000 / 50,000UK
- Koppert (Macro-Mite)50,000EU / GLOBAL
Macrocheles robustulus by target
Rate and timing differ by what you are releasing it against. Each page below is the program for one pest.