While I have "zero" knowledge of Austrian customs, I do have some "ideas" on "human nature"; all people who are in the business of checking travelers at airports, International borders, etc. have many things "in common"; they all tend to be suspicious, serious, "unfriendly", and extremely quick to "pick up on" ANYTHING that is "out of the ordinary", or is something they personally have no knowledge of,( or interest ) in. ( human nature )
The mere fact that probably no more than one passenger in every 50,000 travels with a collection such as yours, certainly doesn't make you "unusual", "wrong", ( or anything else "negative" ). But I must tell you, to these kinds of people, it will make you "statistically different" than the last 50,000 people they have "checked"; that is all it takes to arouse their "suspicion" ! So, you are very wise in "looking ahead" and taking any steps you can to "lessen" these suspicions.
First, I would not mention the word "bug"; to most people, it arouses "negativity"; ( again, human nature )
Next, any time I'm doing anything that I think may seem to anyone watching, as being "less than ordinary", I always try to have a "cover story" ready.........something that leads the "suspicious" customs agent's "suspicious mind" back to "ordinary"
For example, I wouldn't say, "oh, I collect insects"........I would say, "you see, I'm a teacher; I teach entomology to my students in Europe, and I have these "specimens" which I have collected in North America, and which are quite rare or non-existent in Europe, and of course, they ARE ever so "fragile".............so you are leading the suspicious mind back to "ordinary", and placing yourself in a more "admired group", namely a teacher: everyone "admires" teachers !
At the same time, you are very politely letting him know that your "specimens" are fragile, they have great "value", and they must be handled with great care !
While all this is going on, I would be quite "pleasant" ( but not overly "cheerful" ); serious, and above all, I would "exude confidence". ( it's really all about human nature ! ) Confident people have nothing to hide; nervous people on the other hand, "inspire" suspicion ! ( And believe me, Customs agents are "masters" at "reading people" ! )
I really think it's a good idea to do or say anything "upfront" that I have these "specimens"; ( not butterflies, not bugs, but "specimens"........."valuable specimens" to be used in teaching entomology to students. Its all about "helping young people to learn"........
From the time I was quite young, I was very interested in reptiles; in any "group", you mention the word "reptile", 99% of people think "snakes" ! I don't have to tell you how many people view snakes; I learned early on, you must be very knowledgeable about snakes, and why they are so beneficial to people, how they go about their lives, and why they are totally undeserving of the very negative "reputation" they have been given. When I was in my 20's, I was asked to give a "lecture" on snakes and lizards to a group of young children; I had a few common harmless "specimens", a small crocodile from Asia, and a copperhead, ( which are very "pretty", colorfully marked, and rather mildly venomous)
lead people's minds in the direction you choose, if you have knowledge, and you can "put aside" their fears.
Learning how to "impart knowledge" and to "control the situation" while lecturing people about reptiles taught me a lot about human nature.
So from now till you return to Europe, you will be thinking, " I'm a teacher, I help young people learn, I need these "specimens" to help my students learn about entomology. When you reach the Austrian border, you will be CONFIDENT! ( And I predict they will treat you like a teacher, and not like a "suspicious person" !
Good luck, Duke !
Stupidity: Doing the same thing over and over again and expecting a different result; Albert Einstein