Remedies against mealybugs - what do you think?

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Chris L
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Re: Remedies against mealybugs - what do you think?

Post by Chris L »

I've been re-reading the article that appeared in our branch newsletter years ago which is about the life-cycle of a mealy bug. It is really interesting as it explains each stage of the mealy bugs life.

Reading the article again carefully it makes it clear that one method of attack isn't going to be really effective.

I have a feeling the plants need to be stocked up with a systemic from time to time, and coated with a detergent / Neem Oil barrier to kill/starve the eating bug stages, and a contact spray to kill off any egg laying bugs before they lay more eggs. Yellow sticky traps may also attract and kill the flying male bugs.

To break the cycle the First Nymphal Instar, once hatched needs to be prevented from eating on your plants. If they could be starved to death then they are not going to grow into adults. To me the only way to do this without them building up resistance is some kind of neem / soap / alcohol based spray.

[attack 1] A spray every few days for five to six weeks should reduce the eating capabilities of those instars as they hatch (combined lifespan is 4 weeks).

[attack 2] Any visible adult bugs need to be got rid of to stop them laying more eggs.

Here are the stages listed in the article (link to newsletter below)

http://www.manchester.bcss.org.uk/image ... ER1998.pdf
EGGS. They hatch after about a fortnight.
FIRST NYMPHAL INSTAR. 13 days of gorging ensue before it ends this stage by being covered in white wax.
SECOND NYMPHAL INSTAR. ....so overfed that it couldn’t possibly move anywhere. These also last for 13 days after which those destined to be the male of the species spin a white wax cocoon ...
PREPUPA MALE. ...no mouth parts and can’t feed. This stage is a short one of 4 days.
PUPA MALE. This stage lasts some six days, the legs are well developed and the insect is very active.
ADULT MALE. ...The male mates and dies after about 8 days ....
THIRD NYMPHAL INSTAR – FEMALE. It is inactive during this stage at the end of which it becomes the adult female
ADULT FEMALE. These are mobile but not very active. They frequently form colonies of 10 to 20 creatures after mating, each colony being covered in white waxy wool.... Mated females live for about 43 days.
Thus the life span of a female from egg to death will be anything from 90 to 100 days and a male from 55 to 65 days.
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Re: Remedies against mealybugs - what do you think?

Post by Paul in Essex »

A nurseryman friend of mine says he recently trialed a product called SB Plant Invigorator and it wiped out a persistent attack of mealies in his Clivia collection that other methods had failed to shift. I have just got some to try here.
http://www.fargro.co.uk/products/agroch ... orator.asp
www.oasisdesigns.co.uk

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Re: Remedies against mealybugs - what do you think?

Post by purzo »

this was my reply to a similar question a few days ago.
I use a 2 pronged form of attack, cocktail sticks to squish any easy to get at adults and fine spray neem/citronella oil shampoo (diluted to 1%) on juveniles and large groups especially in the crown of plants. I check daily but it's easy to miss some as they seem to have a built in defence mechanism and like to hide on the out of view side of plants. Make sure you check under your pots too and squish any egg clusters (like a pinkish fluffy ball).
This is the actual shampoo description on Amazon: "argentum plus- Silver-MSM Neem 2in1 Anti-Headlice Shampoo and Conditioner 100 ml" . It contains both neem oil and citronella oil. There are a few reviews saying it was effective against head lice/nits infestations but I haven't had the need to test this yet. Anyway, my logic was that if it works on head lice it was worth a try on mealy bugs. I add 0.5ml to a 600ml spray bottle and only spray plants on which I see MBs.

I must add I have less than 1000 plants so regular checking, squishing and spraying isn't a major chore for me and in fact I find it rather therapeutic and gives me something to do when there isn't watering or repotting to keep me busy.
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Gary

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Terry S.

Re: Remedies against mealybugs - what do you think?

Post by Terry S. »

As far as I can gather, there are only really three remedies available to the amateur from garden centres.

Neonicotinoids - the chemical name ends in "prid" and I think that acetamiprid is still available in spite of the efforts of the EU to ban some members of this class because of their effect on bees in the field environment. Branded insecticides keep changing their active ingredients so look closely at the package. These chemical are systemic and will remain active in the compost for some weeks.

Synthetic pyrethroides - the chemical name ends in "thrin" and most only work by a contact process. I think that deltamethrin is the only one presently available to us

Physical killers such as SB Plant Invigorator - insects "breath" through small pores in their body and this class of chemical blocks the pores and suffocates the insects (aren't we cruel?). Because it is not a chemical killer, it is almost impossible for insects to become resistant. Furthermore, this is the only one of the three classes of compound mentioned that will kill red spider mite.

Having said all this, I alternate all three treatments in my collection and can still not completely eradicate mealy bug. In the days of organophosphorus nerve poisons I did not normally see mealies in my greenhouse. They are now a genuine problem.
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Re: Remedies against mealybugs - what do you think?

Post by widea »

The reactions are very interesting, thank you.
Reading and summarizing this for myself, the best longer term attack seems to be an alternating combination of a systemic and a 'surface remedy'.
A question though: I noticed mealybugs mysteriously disappeared on cacti that I put outside. Inside the house I could hardly exterminate them but shortly after I put them outside there where no mealybugs to be seen.
Are insects to blame for this or could there be an other factor playing a role in this (that we hopefully overlooked)?
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Re: Remedies against mealybugs - what do you think?

Post by Patrick »

As I've said many times before I use neem oil which I water on the soil in dilute form with a little washing up liquid, 2 or 3 times per year. It is really beyond me why more people don't do the same. It worked for Doug Donaldson and I have not seen a mealy or used any chemicals at all in all the years I've been doing it. But it would seem that folk just don't want to believe that it works! :roll: I buy it from the neem team.
Last edited by Patrick on Sun Jun 11, 2017 11:12 am, edited 1 time in total.
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Re: Remedies against mealybugs - what do you think?

Post by purzo »

Patrick wrote:I use neem oil which I water on the soil in dilute form with a little washing up liquid, 2 or 3 times per year. I buy it from the neem team.
Could you give your exact dilution rates please Patrick? For the neem oil and the washing up liquid.
Cheers
Gary

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Patrick
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Re: Remedies against mealybugs - what do you think?

Post by Patrick »

purzo wrote:
Could you give your exact dilution rates please Patrick? For the neem oil and the washing up liquid.
I do exactly what Doug Donaldson recommended which is "5ml (1 teaspoon) of neem oil per litre of water, plus up to a teaspoon of detergent to thin the oil. Mix well in warm water, add to watering can with cold water and stir well. Do it after first watering, June or July and late September."

I usually mix enough for a full 10 litre watering can in a jug at the kitchen sink, so 10 teaspoons of neem with maybe 6 or 7 of washing up liquid in hot water.

I buy a litre of utility grade neem oil, you have to warm it up before use as it solidifies when cold.

Doug used to bring neem oil back from India when he visited on his Cactus & Succulent travels.
Last edited by Patrick on Sun Jun 11, 2017 11:11 am, edited 1 time in total.
Patrick. Small varied collection of North American, Mexican and Andean Cacti. Variegated Agaves and Echeveria. Developing a succulent garden in Portugal. Joined Somerset BCSS and forum in 2007.
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Re: Remedies against mealybugs - what do you think?

Post by Tina »

Hi P,
I think you mean Doug & Doreen Donaldson
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Re: Remedies against mealybugs - what do you think?

Post by Patrick »

Tina wrote:Hi P,
I think you mean Doug & Doreen Donaldson
whoops sorry, yes I do, thanks Tina
Patrick. Small varied collection of North American, Mexican and Andean Cacti. Variegated Agaves and Echeveria. Developing a succulent garden in Portugal. Joined Somerset BCSS and forum in 2007.
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