Updated: Aug 30, 2021
The answer to that question is no, but you can learn as much - or as little - Latin as you want to know and learn. Like so many things, angling entomology knowledge and interest occurs along a continuum. At one extreme are the anglers that knows the correct Latin names of nearly every insect they encounter and really fly fish for the bugs - but they would NEVER call them bugs. At the other end of the continuum are the people that 100% do not care about the bugs, they are going to "chuck big ass streamers" no matter what. Neither end of the spectrum are right or wrong, just different.
I have known fly anglers that are amateur entomologists - and a couple that are professional entomologists - and others that probably know a mayfly from a stonefly from a caddisfly. Any of them can be really good - or not so good - anglers.
Being a science geek, I fall fairly far - but I think not too far - on the entomology side of the continuum. There are many anglers that have forgotten more than I ever knew or will know about aquatic entomology and on the other hand, I probably know more entomology than most anglers. Why I was interested in aquatic entomology was that I was at the point where I was learning a lot as a fly angler, really soaking in knowledge, and knowing the hatches seemed to be what learning anglers did. And without question, better knowing and understanding the hatches made me a better, more successful fly angler but it probably was not necessary for that to happen either. I knew a lot more angling entomology 20 to 30 years ago than I do today - but some of it stuck.
Learning about "the bugs" - their names; when, where, and under what conditions they hatch; and all the other aspects of aquatic entomology can be pretty daunting. There is A LOT to know - but only if you want to. I think this is where people struggle with trying to understand angling entomology - they go too far, too fast. You do not need to know the Latin names - it helps you communicate with others - but the common names work most of the time. I know a lot of the Latin names I once learned and I find in my older books are not correct any more as taxonomy changes (that's science!). You do not need to know every hatch but really understanding the half dozen most important ones will improve your success.
The number one reason that I think knowing about the insect hatches helps make you a better, or at least more successful, fly angler is it helps put you on the water when fish are most likely to be actively feeding. If I know that when Grannom Caddis (Fox Valley TU video above) are going to hatch mid-day beginning in the middle of April on my local streams, that puts me on the stream during what is probably our best and most consistent hatch of the year. My best dry fly fishing of the past five years have all been around the Grannom hatch so now I plan around that hatch. The Hex hatch (in photo above) occurs after dark and the spinners (reproductive adults) are generally more important than the emerging duns. There are some species of caddis that dive underwater to lay their eggs which means that fishing standard dry flies are likely to be less effective than wet flies or soft hackles. These pieces of knowledge are bound to make you a better angler, at least in terms of the number of fish caught. And the information to better understand the insects has never been more plentiful and accessible (see the video above as a great example).
What You Need to Know
Let's start which what I think you do not need to know - the Latin binomial names of tens or hundreds of insect species is unnecessary. If you really get into the whole fly fishing thing, as some point you are bound to learn a bit of Latin. The Hex hatch - one you are bound to have heard of - comes from Hexagenia limbata, a giant yellow mayfly that is widely distributed across much of North America. The species goes by any number of common names; giant mayfly, shadfly, Golden mayfly (or drake), Green Bay fly, Michigan mayfly, or simply "the hatch" but most commonly it is referred to as "the hex", a shortening of its Latin name. See, we all know some Latin. How much more you want to learn is up to you.
The bare minimum, in my opinion and experience, is being able to recognize the four most important aquatic "bug" groups (orders) - mayflies, stoneflies, and caddisflies along with midges and knowing a bit about when you should expect them to be important. That is, a somewhat well educated angler should know how to identify a bug in hand or on the wing to the order in which it belongs. Order is a pretty coarse designation. In the mammal world, they are as different as us (primates), bats (Chiroptera), cetaceans (whales, dolphins, and porpoises), and marsupials which are each a different order. And I think it would serve all anglers well to know enough about the top three to five hatches in their area. By knowing enough, I basically mean knowing when (time of the year and day) and where (which streams, habitats within the stream) they hatch. It would be useful to know what stage you should be imitating as well...more on all this to follow.
Adult aquatic insects are pretty easy to tell apart by their wings. Mayflies (order Ephemeroptera) have upright wings - often compared to "little sailboats", the others have "down wings" but each of these are quite different. Caddis (order Trichoptera) have a tent-shaped wing, Stoneflies (order Plecoptera) have wings that lie flat over their backs, and midges (order Diptera) as their order name suggests have only two wings (Di = 2; -ptera = wing). Identifying them as aquatic larva is only a bit more complex. Two groups - the caddis and midges - are often described as "worm-like" with caddis having two "anal hooks" which is a simple differentiator. Many of our caddis species build a case or retreat held together by silk. Stoneflies and mayflies are the "classic" insect shape with distinct abdomen, thorax, and head segments. Mayflies have two or three tails and stoneflies always have two tails. The gills on mayflies are on their abdomens and stoneflies have thoracic gills. And any Driftless angler should certainly know what a scud / amphipod / freshwater shrimp is - they are the most common invertebrate in the photo below as well as in many (most?) of our streams. And if you know that, you probably know enough to be reasonably effective when you come across a hatch.
Just a quick bit of terminology - all aquatic insects are aquatic macroinvertebrates but not all aquatic macroinvertebrates are insects. Insects (class Insecta) are defined by their six legs which are jointed and their three body segments - head, thorax, and abdomen. Aquatic macroinvertebrates is simply the ecological catch-all term for any number of non-vertebrate species that are mostly insects and crustaceans which include crayfish (decapods), scuds (amphipods), and sowbugs/cressbugs (isopods).
A case for knowing some Latin
First, the Latin names of the orders tell us something about them. Diptera have two wings, mayflies are short lived as adults ("ephemeral"), Trichoptera (caddis) means "hair wing" and a close inspection of their wings will make this evident, and lastly, the order for stoneflies, Plecoptera, means "braided wing" and refers to their rather complex wing vein patterns. The larger point, knowing a bit of Latin is useful because it is often informative. The EPT taxa (Ephemeroptera, Plecoptera, and Trichoptera) are often used in measures of "stream health", water quality, and indices of biotic integrity. The same often - but not always - goes for the genus and species epithet of particular species.
Maybe the best best reason for learning a little more about the Latin names for 'bugs' is that you can better communicate about the hatches. Common names are often quite useless. What a sulfur mayfly or a black caddis means to you may depend upon where you live and how you learned about the 'bugs'. But for those that know the Latin names, there is no ambiguity when I talk about the Brachycentrus, Glossosoma, and Chimmara caddis hatches - all which might be called called black caddis by anglers. This is why binomial nomenclature - the use of genus and species - was developed, to make there be one common way that all people, scientists in particular, referred to a particular taxonomic group. In using scientific names, it is a way to communicate across languages.
An alternative approach
There is little need to know all this Latin for most anglers. First, much of angling entomology can be done by approximation. The Adams does not represent anything in particular but in its many configurations, it imitates no shortage of mayfly species, big and small. Nor does it take a genius to know that "blue-winged olives" or BWO are olive mayflies with a blueish (really, mostly gray) wing. BWOs are taxonomically very diverse but honestly, does that really matter if you know that they run from a #14 on the large size down to as small as you care to tie on the small side. For caddis, I am fishing a CDC and Elk most of the time and hopefully I am able to get a good look at a natural to know what size to fish but ninety-some percent of the time it is somewhere between a #14 and #18. At least for Wisconsin, there are so few stoneflies that you can more or less ignore them. And carrying midges in light and dark and then some clumped patterns like a Griffith gnat will work just fine. An angler in the Driftless Area should certainly know about scuds which are often the most common and important macroinvertebrates in most high productivity streams.
Sure it would help to know more but a decent hatch chart - and there are many - and observing what is happening around you is really all that is needed.
For the next angling entomology post, a bit about life cycles and things to look for in Wisconsin streams. For now, some sources to better know and understand Wisconsin hatches.
Wisconsin Hatch Charts
Driftless Wisconsin Hatch Chart (one I did many years ago; Silver Doctor Fly Fishing)