Whaaaaat, are you kidding? Sure, real bugs don't emote, but many of them have GIGANTIC EYES, which are basically free real estate to any cartoonist worth their salt. ^^ Use what nature is giving you.
So based on what you said, I feel like what you're having a hard time with is understanding how to make varied designs look unified in theme.
@Pony_wearing_a_hat 's suggestions are all pretty much it: you just have to have a base design you can deviate from, and give each major villain their own unique variation.
I got some relatively recent villain designs I'd like to use to illustrate my point:
So you can see that they're all kind of liquidy in theme, and they've got a lot of features in common: the holes in the bodies (most notably, the face-like pattern over the torso), the patches of "flesh" that peek through their signature colors, the eyes, the capes, etc.
But each one was designed with their character concept in mind:
-Red is the "star", and he was the first design, so he became the "base" for the others. But even so, the giant heels and the big hair give off a "look at me" vibe that matches his flamboyant personality.
-Black is a much more guarded, aloof character, so she has way fewer flesh patches than her peers (it's really just the shoulders ^^) and the lower part of her torso pattern becomes a sort of skirt that obscures her figure. Her hair envelops most of her body, and takes the place of the cape from the base design.
-White is the quintessential "sexy lady" design, with the flesh patches on her legs becoming so large that what's left looks like garters. The "liquid fringe" over her shoulders adds a touch of delicate elegance~
-Yellow is the "big brute" archetype, so obviously he has a much thicker body than his sprightly peers, including extra holes in his torso (reminiscent of abdominal muscles). He also has the longest and sharpest shoulder spikes.
So yeah, just four baddies (and these are only first-pass designs, they can definitely be improved) but you can see what strategies and techniques I used.
I really recommend you share pictures of your own designs so that people can critique them, or at least judge whether they're as bad as you seem to think. ^^;