Yes definitely spider mites. Like most products for spider mites you will have to make contact with the spider mites to kill them. There are some products such as Avid that are translaminar which means if you spray the top of the foliage it will go through to the underside of the foliage. Also, most products only kill the adult spider mites or just certain stages of the life cycle. You have to remember there are adult spider mites, larvae and nymphs emerging from eggs plus the eggs. Some products kill them all while others don't. I believe the chemical in the Bayer 3in1, tau-fluvalinate, is a contact miticide so you would actually have to make contact with the mites to kill them and it won't kill the eggs. And I know I read on the label that the Bayer 3 in 1 was only systemic for the other things and ot spider mites. I couldn't find it on the label online but I know I read it when I read the bottle last year. You would need an Ovacide for that or keep spraying. But whatever you use it has to be a miticide
The general consensus is to spray 3 times one week apart so you will kill any new mites that may hatch. The life cycle is different depending on the weather I , the hotter it is the faster they breed/hatch. There whole life cycle is 5-20 days depending on the temps. The eggs can hatch in as little as 3 days so some people spray every 3 days or 5 days.
Spider mites CAN kill a daylily so try and keep them under control. You can use Horticultural Oil to kill them as long as you make contact with them; it suffocates them. The big problem with the spider mites is that they are on the underside of the foliage and they are hard to get to if you have big clumps with lots of foliage.
