Yeah, sorry if I changed the subject -- to answer your main question, I don't know if eucalyptus attracts bears. Hopefully someone knows more. Eucalyptus is also safe, as far as I know. I do know there have been concerns about pyrethrums, though. I imagine that in a lot of cases you take something that is probably fine in normal amounts and then concentrate it to such a level that it can cause some weird things. Unfortunately, many of these things (natural or lab based substances) aren't tested for years before they are put into products. Again, I don't want to seem alarmist -- most of this stuff (including DEET, for all we know) may be perfectly safe. I just figure it is safer to not worry about it.
As far as heat is concerned, a wind shirt breathes fairly well, so I don't get too hot (I can take my normal shirt off). Bugs are mainly a problem when I'm not moving (like in camp) so I prefer the wind shirt. Wind pants are a bit annoying, as my favorites (Montbell) only come in black, so they can get a bit too hot. It's a small price to pay for when they are out in full force.