I have studied different insects for my entire academic career, but I've never had to work with live specimens before. I am considering a project where I will need to capture live dragonflies and look at their wings under our SEM. However, I will likely need to remove the wings from some live specimens. For this question, assume that is my only option. Several papers might come from this project, and I'm not sure what ethical considerations would need to be addressed when preparing or submitting the manuscript.
Apart from one's personal moral considerations, research studies on live animals are overseen by an Institutional Review Board (IRB). Organisms collected from the wild will likely require some sort of permit.
Check the rules for your institution's IRB. Insects usually don't require special approval so you may not need to submit a plan, or you might submit one and it would be waived. (But don't listen to me, check with your IRB.) If you're proposing pulling the wings off while the animal is alive, and the IRB wanted to get involved, they could work with you to find ways to minimize the animals' suffering.
For collecting the animals, determine where you will get them and who manages that land. You will need their permission to collect, and if the manager is a government agency, that would require some kind of permit. Try to get these submitted well in advance (like months) since those approvals move at the speed of government. You will need to state exactly what you want to collect, justify why you need to make the collection, and probably discuss mitigating factors.
If the organisms have any kind of special status, like being rare, endangered, or invasive, you might need even more permits. Check for any laws applicable to your jurisdiction.
Finally—this isn't required by as many journal as should require it, but it's still a very good idea—have a plan for how to voucher your specimens. Vouchering is a way to keep your specimens available in perpetuity so the scientific community can check and build on your work. For the dragonflies this would be an entomological museum. If you're unfamiliar with such a museum, find your nearest one and talk to the manager there about how to go about making a proper specimen (you may even be able to store the actual SEM samples with the rest of the specimen, which would be great for future work).
Different ethical systems will give different answers to such a question, depending on how they consider insects to have independent rights, such as a right to life or to not be injured. Even the Dalai Lama, it is said, will swat at mosquitoes, though Buddhism has a high respect for all life.
But, in the US, to convince a journal that you have acted ethically, you run your research proposal before an ethics board, such as the IRB (Institutional Review Board). They will make a determination whether what you propose is ethical or not.
That isn't a perfect solution, of course, since the members are also people, but, I'd think that the recommendations of the IRB would be "conservative" enough that few would object (not none, however). But it gives you formal permission to act that will almost certainly be accepted by a publisher.
As noted in comments, the IRB is for human subjects, but a more general ethics board might be available, even one specifically for your field.
There is ethical danger, however, in making up your own rules without some outside, independent consultation. Too many past research projects have fallen into serious difficulty when that is done.
Note that this question has been examined in the literature. A google search for "ethics of experimentation on live invertebrates" turns up a number of papers.
One of the most bizarre things across the various ethical standards that government agencies in many countries require one to meet, is that insects are not recognized as requiring protection. Insects are invisible; they simply fall outside the purview of most country's IRBs (e.g., note for example, the scope of the Australian code, as described on page 1 of the requirements). I think it is correct to say that, in the UK, it is harder to experiment on oneself than it is to pull wings off a fly.
On a slightly different note, I appreciate your request that responders view your proposed activity as being your only option. But as with most ethical choices, there are other options ... in your case (and I am not asserting a moral imperative here, merely an option) the alternative is not to do what you a proposing.