Replacing the euonymus with another kind of shrub entirely would definitely take away the recurring euonymus scale infestations.

Does this "scale" affect other plants? Also, where does it come from?

Yes, it can infest other plants: camellia, celastrus,
ivy, hibiscus, holly, ligustrum, boxwood, honeysuckle, pachysandra and daphne can all become infested but problem is usually worse on euonymus.

As to where it comes from.........where does any insect problem come from? They can piggyback in on other plants; in the crawling stages, it could come into a garden via wildlife or the wind (possibly under its own steam!) and sometimes they just appear. I'm almost inclined to believe there's a bit of spontaneous generation going on with some insect problems - lol!!

to be very frank.. even though my name is ken ... THIS IS WHY I GOT RID OF ALL MY euonymus

they are a carp plant.. subject to this problem... and just not worth the chemicals.. oils.. and time ... and exposure ..... to deal with them ...

if you cant find something much more extra ordinary... to fill the spot.. that will be completely carefree... you arent trying very hard ...

ken

ps: i wasted a lot of money on bayer systemic tree and shrub goo to battle this.. before i wised up.. and shovel pruned the things ...

Plus, depending on where you are, many Euonymous species are proving to be invasive. Other than such excellent but rarely-used native species, like eastern wahoo, etc. I'd not waste my time with any of the imports.

+oM

spray with diluted soapy water it always helps when I get these things on plants