Is there another level behind the invasion ?

The question has been brought up repeatedly in the series: "Who or what is behind all this?" Is this simply an infection of the Earth by an otherworldly source, or was it intentionally done by some intelligence / "invasion force" yet to be seen?

When the very same topic was touched on by C.J. Carella, the writer of the GURPS Chtorran handbook, not only he but also David Gerrold himself (in his foreword) testify that while compiling it he had full access to the existing (circa 1993) written pages of A Method For Madness. Other than reading the source material ourselves, we can only extrapolate what information Carella was given.

So, while re-reading in an effort to come across clues I may not have noticed before, I see a picture on page 81 in the margin of what looks like some gargantuan, wampa-like creature that dwarfs the worms in size and is also being looked up to / worshipped(?) by them. It is on the same page as the description of Chtorran Nests, in which Carella writes: "Who knows what stage may follow the 'cities,' or what monsters will appear next?"

At first I believed it was a view of a gorp from afar... but the scale of the worms in the foreground puts its size in perspective. Could that silhouette be what we haven't seen yet? Is Carella implying that some enormous beings are the actual Chtorrans, this sketch of which is approximately how they appear?

Carella also writes a more telling passage on page 114:

...With the Earth's population drastically reduced and contained by the
Chtorran ecology, this might be the time for the intelligence behind the
invasion to show up. Some scientists believe that the worms are "feral
children," immature versions of the real Chtorrans. Imagine if their
parents come as an army of even larger worms, equipped with ultra-
tech equipment. Their numbers would not be great (if it had been possible
for large numbers of mature Chtorrans to be brought to Earth, it would
have happened already), but their arrival could tip the balance once again
in the aliens' favor.

Or perhaps the "true" Chtorrans are nothing like the worms; they might
be more evolved versions of the bunnymen, or an altogether different
race. They could be a race of instinctive cowards (in a world heavily
populated by the Chtorran worms, it might be one viable way for a
species to develop intelligence), which would explain their roundabout
tactics in displacing humans from the planet. Or they might be already
extinct, the invasion a pre-planned attempt to begin anew somewhere
else, an ultra-tech Noah's ark aimed at Earth. This possibility is the most
comforting (it would mean that once the enemy is beaten, there will be
no reinforcements).

With this in mind, I am starting to believe that we haven't seen it all yet. Before, I was sure there was nothing else. Now... I'm not so sure.