It's a pity that the "The Web Planet" isn't actually very good and, indeed, at times doesn't merely verge on the ludicrous, but smashes right through the ludicrosity barrier and just keeps on going. It is an attempt to do something different with Doctor Who and the lore has it the failure of the story is the reason why we've been pretty much stuck for the last 47 years with either aliens who look exactly like humans or aliens who look exactly like humans in rubber suits. In fact, in "The Web Planet" we aliens who look exactly like aliens in rubber suits (butterfly-humans and weevil-humans), but at least they were making an effort and the Zarbi at do look like giants ants rather than ant-humans (OK, OK, giant ants with human legs). As for the venom grubs, well, I think we have to remember that all of this probably made a whole lot much more sense to the average viewer in 1965 than it does today. The heyday of the cosy duopoly was an era when ITV could show opera in primetime and "The Web Planet" is best thought as a piece of experimental ballet-theatre (indeed the Menoptera were choreographed by a choreographer from the Royal Ballet). In many ways, NuWho - modern television in general - is much more sophisticated than Classic Who. But most viewers in 1965 with access to at the very most three channels and would have had a much more varied and richer televisual diet than many viewers today, Sky Atlantic and boxed sets of The Wire notwithstanding. Today the notion of spending six weeks doing experimental ballet-theatre on kids' sf show in primetime seems unimaginable, but in the mid-60s people would have seen it as another part of the televisual tapestry and thought little more of it. Whether they liked it or not is another matter and certainly this kind of thing wasn't tried too often again (but see, for instance, "The Underwater Menace", of which we now have a whole extra episode to look forward to), but "The Web Planet" definitely made some kind of impact at the time. Doctor Who and the Zarbi was one of the three DW novels published in the 1960s and the first DW annual is full of the Zarbi and the Menoptera, including, of course, feature them in living colour on the cover. OK, they didn't have the rights to the Daleks and I think the Voord are in there somewhere too. If only "The Web Planet" had had a more engaging story and they had somehow managed to transcend the limitation of the budget and the available technical resources, we might have enjoyed a much more varied range of aliens over the last decades. Or at least we'd have more period curios to look back at and ponder upon.
Now Write On... Just imagine a sequel to this with modern effects. And a half decent plot. OK, OK. That's never going to happen. There was saying current in the Moorcock New Worlds era that the only truly alien planet is Earth. I recall Steve Gallagher opining that all aliens are really humans in rubber suits. But the one thing that an actual alien wouldn't be is a human in a rubber suit. Pace Wittgenstein, if an alien could talk, we would not understand ver (see, for instance, "The Creature from the Pit"). And it's pretty clear from the last couple of decades of planetological research that there are some really wacky worlds out there (not that plenty of writers haven't come up with those without recourse to the latest scientific thinking). So someone should take half a leave out of Hal Clement's books, but add in psychology that is a product of the aliens' evolutionary history. Imagine a story set on a hot Titan orbiting a gas giant around a red dwarf. Gravity would be so low that flight would be easy in the thick atmosphere. And just pick an interestingly different (to humans) reproductive strategy and imagine the consequences extended to a technological civilisation. I am sure we can do better than "The Power of Kroll"