Yes that is correct.
I'm not sure of the soap/water ratio,maybe someone else can jump in and
help you or you can go to google.com and find out what the ratio is.
I wouldn't recommend doing in the heat of the day,as it may burn your
plants.
I've also heard a strong stream of water from the hose will wash them
away,but I would just treat them with the soapy solution.
Be sure to get the under-side of the leaves,most importantly.

I'm sure some others will have more 'tricks of the trade' to share.

Hope that helps....
Breezy~zone 9