Scale insect

Maarten van Helden Maarten.vanhelden at
Tue Aug 15 09:44:06 EST 1995

In article <Pine.SOL.3.91.950814133324.13543B-100000 at>, 
ez023517 at says...
>I also have quite a problem with scale insects and this is what I know:
>As for the life cycle those round raised bumps are the adults and you can 
>easily pick those off because they don't move far but the younger stage 
>is where the problem is because the little nymphs crawl around and spread 
>everywhere.  You don't need to wash off the roots, I don't think they get 
>down there (I haven't seen it anyway).  Up to seven generations can be 
>born in one year.  
>An indepth control method is to monitor when the nymphs are most active 
>and to treat the plant then.  Do this by putting double sided tape around 
>some of the branches and keep track of the intervals in which there are 
>th most crawlers and then treat them the next time you predict them to be 
>active.  All the while picking off the adults.
>A less indepth method is to spray the plant with a mixture of alcohol and 
>insectidical soap.  I had success on an Hibiscus by just painting on some 
>soapy water from a cup of water and a bar of ivory soap with an old 
>paintbrush.  I heard later though that you could add the alcohol because 
>apparently it helps the soap to penetrate.  
>By any chance are the plants affected ficus?  That is where I have my 
>Good Luck!

It is true that ficus plants are most often affected by scales. As for you 
chemical treatment I would suggest to use a systemic insecticide (taken up 
by the plant into the phloem on which the scales feed). Some of these systemic 
carbamates like pirimicarb (pirimor) are relatively specific for phloem 
feeding insects. Insecticidal soap etc is often not very effective becasu of 
the scal which acts as an extra barrier for the liquid and therefore this does 
not rach the insect.

I doubt that you will find any synchrionisation in the production of the 
crawler stage. you probably have a population of mixed age and therefore a 
contineous production of offspring.

||\\  //||  Dr. Maarten van Helden
|| \\// ||  Dept. of Entomology
||  \/  ||  Wageningen Agricultural University
||||||||||  Binnenhaven 7, 6709 PD
||      ||  Wageningen, the Netherlands
||      ||  Tel +31-8370-85118 Fax +31-8370-84821
||      ||  Email: <maarten.vanhelden at>

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