Don't know about the eggs but you can handpick the grubs because they have the revolting habit of sitting inside a blob of their own excrement and are hence easy to spot. The adults drop to the ground as soon as they are disturbed so you need to cup one hand beneath them as you attack.

The eggs are quite distinctive small orange spots on the underside of the leaves in spring. If you check your plants at 6" tall then 12" you can rub them off easily preventing the population from becoming a problem. This becomes a big job if you have a number of lilies.

I find now that the squirrels have destroyed most of mine that I really do not have an issue with the few that remain. There is always an upside if you look hard enough lol!

Sorry to hear about your Lily beetles! I have given up the fight because it got to be too much work. Neem oil is ineffective against the adults, but you can spray underneath the leaves every 5-7 days to kill the eggs and larvae. The eggs are a small, orange cluster under the leaves which you can wipe off. Like floral said, the larvae cover themselves in their sh-t; they are the real eating machines. They hide under the leaves as well, more concentrated on the lower leaves I found. Again you can wipe them off; I got much less squeamish over time and squished and wiped with my bare hands. There is a certain satisfaction with squishing those little b's. Pyrethrum based sprays and rotenone has been found to help kill off the adults and eggs/larvae. The adults bury in the soil for winter; in the spring stir up the soil around the lilies and you can squish them as they emerg. Btw, they also like other members of the Lily family such as Solomon Seal and Frittilary. I did find that they were more concentrated in the sunnier portions of the garden so I have kept a few of my lilies that are in a shadier area and my Martagons which I could never give up. These pests are a real scourge!

The eggs are really easy to see/spot. They are red, laid in lines on the underside of the leaves and can be squashed if you're not squeamish! Google lily beetle eggs and then click on the Images option and you'll see how recognizable they are. I don't know re Nrrm oil and the beetles/eggs/larvae. I've just largely given up on lilies! A few survive on their own and I ignore the ugly stage ;-) Regal likes, in my experience, aren't quite as much a target as others - although if you just grew a lot of the Regals, I'm sure the beetles would adjust their preferences... :-(

Some great info above.

I killed adults in the soil as Debbie says, but have now given up on lilies.

One minor qualification: we have had a lot of Solomon's seal and none was ever affected by lily beetles. Solomon's seal (a Polygonatum) has more recently been reclassified out of the lily family. Suspect the fact that it's not prone to lily beetle damage could be taken as trivial support for the reclassification.

The lily family member that I unfortunately had to give up on was toadlily (Tricyrtis). Have never used any Fritillaria.

Way back I seem to recall these nasty creatures were referred to as Fritillaria beetle but since more people grew Lilium the name adapted. I never had any beetles on my Fritillarias but again the squirrels and chipmunks destroyed them and now I am only left with a few F. meleagris.

SB what a shame you had to give up on Tricyrtis. So the beetles attacked them? I enjoy their late season show and would be very unhappy to have them affected.

Interesting about the Solomon Seal and glad to hear it as I enjoy my clumps of it and would be very upset to lose them. I have on occasion seen the odd Beetle on mine but just assumed they were not prolific because of the plants placement in the shade. I have no Frittilary for that reason and didn't find tricyrtis hardy for me. I'm sorry to hear they wiped out yours.

I've never actually seen the eggs. I only have a few lilies and I tend to keep a close eye on them from May onwards. I often nab mating adults so maybe they don't get a chance to lay eggs. I find they'll go for L regale rather than L henryi. I don't grow any asiatic types. There are some good pictures of eggs, larvae and adults at this link. https://www.rhs.org.uk/advice/profile?PID=553