I can't be 100% sure but they look like lacebug eggs. Whoever they are, it is insect eggs and to rid yourself of them spray with neem. BTW neem is for scale too.
Not lacewings, lacebugs. They are two different insects. Lacewings are beneficial. There are many species of lacebugs and it may not be lacebugs but it is an insect. What type of scale do you have, hard or soft?
A little info on scale. You have hard scale. Soft scale is white and fuzzy and some varieties move around. Hard scale is like a barnacle. It is attached to the plant and cannot move, ever. When you kill it you cannot tell if it is dead or not as it is stuck to the plant and cannot fall off until the plant grows enough to dislodge it. If you have been spraying with neem more than 3 times it is dead and it will remain there for a considerable time but keep spraying neem once a week to kill all of the eggs. Neem oil kills eggs by suffocation so multiple applications are necessary to kill new eggs. When no new eggs show up stop spraying neem. In a greenhouse it is much more important to have a spray regimen than if planted in the ground. You really don't want to have any kind of infestation. Neem is good for eggs and hard scale but a spinosad based insecticide is much, much better for all of the other insects such as whitefy who love to inhabit greenhouses.
The secret to spider mites is to disrupt their reproductive cycles and it is difficult to do so. Basically it is to completely eradicate the first to show up and to treat the soil to kill the eggs. Spinosad works better on the actual insects but neem is better for the eggs in the soil if used as a drench. They have a very complicated reproductive cycle and I think you will find it a great benefit to research this.
