Cryptolaemus montrouzieri
A small Australian lady beetle, 3–4 mm long, dark brown with an orange head and tail, sold to clear mealybug colonies in greenhouses, conservatories and on houseplants. Adults and larvae both eat mealybugs, and females lay among the mealybugs' cottony egg sacs, so it works best on a colony that is already breeding. Its larva is covered in white wax and looks like a large mealybug. It is on your side, so leave it alone.
At a glance
- Mode
- Predator — adults and larvae
- Rate
- 2–10 /m² per release, or 5 per plant
- Ships as
- Adults, 100–5,000 per pack; also as larvae
- Temp
- Best 22–28 °C; slows below 16 °C
- Humidity
- 70–80% RH best
- Setting
- Greenhouse, interiorscape, houseplants
How it works
Adults and young larvae eat mostly mealybug eggs. Older larvae take every stage, and one larva eats about 250 small mealybugs over its development (UC puts it at more than 250 nymphs or over 1,000 eggs). Females lay 400–500 eggs over a life of about 50 days, among the cottony egg masses of the mealybugs, and UC notes that the beetles need mealybug eggs to stimulate their own reproduction. That is why the beetle belongs on a breeding colony rather than on a light infestation. When mealybugs run short it will also eat soft scale and aphids.
It is a tropical species, introduced from Australia, and does not tolerate cold. Rincon-Vitova gives a full life cycle of about 31 days at 27 °C and 45 days at 21 °C. UC says reproduction slows sharply below 20 °C; Biobest says activity drops off below 16 °C, and Koppert gives 16 °C as the minimum temperature for use. Ants that farm the honeydew guard the mealybugs, and UC, Rincon-Vitova and Biobest all say to control them. The larvae grow to about 12–13 mm, more than twice the size of an adult mealybug, and they move faster than mealybugs do. Seeing them is the best sign the beetles are breeding.
Is it established?
The adults you release are only the start. What you are waiting for is the larvae of the next generation, in the same colonies.
- DAY 1Small dark beetles with orange heads walking through the colonies
- WEEK 1Tiny oblong yellow eggs among the mealybug egg sacs
- WEEKS 2–3White, waxy larvae up to 13 mm, faster than any mealybug; check now and release again if none
- MONTHS 2–4Uninfested new growth on the treated plants
Release & handling
Beetles arrive as adults in a box or tube and may be sluggish at first. Arbico says they revive within about 20 minutes in fresh air and indirect light. Release them as soon as possible. Unlike most bugs sold, they must not go in the fridge: Arbico says refrigeration harms them, and Rincon-Vitova says not to chill them below 10 °C.
Release the same day
Arbico says to use them within 18 hours. Koppert allows 1–2 days if necessary.
10–15 °C, dark, no fridge
Koppert's storage range. Arbico gives 16–27 °C away from direct light. Do not hold them longer than a day or two.
Evening, at the colony
Release early morning or evening onto infested plants. Bright light makes them fly, and they are drawn to light colours.
Ants off, vents screened
Control ants with barriers or baits, and screen vents and windows so the adults stay.
Pesticide sensitivity
Rincon-Vitova says most pesticides are not compatible with the beetle and spreader-stickers may harm it, while most fungicides should be safe. Check each product before spraying. Check a product →
When to choose something else
The mealybug destroyer is the strongest option for a big, breeding colony in a warm room. Choose something else when:
- The infestation is light or new, with few egg sacs — the beetles need mealybug eggs to breed, so wipe or spot-treat instead
- The room averages below about 16 °C — green lacewing larvae work down to a 12 °C average
- The mealybug is the long-tailed species — it has no egg sacs for the beetle to lay in, so expect slower results
- Ants are tending the colony — deal with the ants first, or they will drive the beetles off
- It is citrus mealybug and you want a specialist parasitoid as well — Koppert sells Anagyrus vladimiri (Citripar) for it; Leptomastix dactylopii also works alongside but is now hard to buy
Where to buy
Suppliers listed alphabetically, not ranked. helpfulbugs takes no commission and does not sell insects.
- Arbico Organics100 / 250 / 500 / 1,000 / 5,000 adultsUS
- BioBee (BioCryptolaemus)250 / 500 adultsUS
- Biobest (Cryptolaemus-System)500 adultsEU / UK
- Buglogical100 / 250 / 500 / 1,000 adultsUS
- Koppert (Cryptobug, Cryptobug-L)500 adults; 1,000 larvaeGLOBAL
Cryptolaemus montrouzieri by target
Rate and timing differ by what you are releasing it against. Each page below is the program for one pest.