I didn't notice any stippling on the needles themselves, if that's what you're meaning. How are the the brown needle clumps produced - do the [spiders, mites, spidermites???] kill the needles (by sucking or chewing on them)? or do they just gather them (and the cause of needle browning and drop is different)?
I fugured the shed needles were from seasonal needle drop and they just stuck to the silk.
Hard to say from a pic but there could be some other critter I'm not familiar with or some minor foliar fungal issue.
Horticultural oil at 2% will take care of your mites and adelgid. What rate did you apply the imidacloprid at?
Keep in mind yearly applications of imidacloprid are not necessary to control adelgid. I've seen mite outbreaks from yearly apps.
1 app at .2 oz. per inch of dbh should give you at least 5 years of control for adelgid.
Foliar apps of Zenieth 75wsp are labeled at 1 pack (1.6 oz.) per 300 gallons. I would go back and check your mix rate. If you are using it that high that would explain the mite outbreak.
Hort oil will kill mites on contact but has no residual effect. Coverage is essential to good control.
I believe we did 1 packet (1.6oz) in a gallon of water to treat dbh of 24 inches, which equates to 0.067 oz/inch. Perhaps we're way to low and should be treated dbh of 8 inches with the same 1 gallon solution? Label appears to indicate 0.1-0.2 oz/inch range, so 1 packet should treat 8-16 inches DBH?