The Energon Pub

When did they arrive on Earth?

I bet the Insecticons arrived on Earth 5 millions of years ago, 1 million before the Decepticons on the Ark. BUT it appears as they were only "awaken" during Season 1, and the computer made them transform into gigantic robot insects.

What about the Constructicons? They were Decepticons who created Megatron. Then dropped their affiliation with Decepticons and turned into Autobots. Then they were definitely brainwashed by the Robo-Smasher and turned into a Gestalt. Then...
???
It appears like Megatron provided them with earthlings alternative modes, anyway.

My own personal ideas:

Given the size of their pod, I think the robots that became the Insecticons we aboard the Nemesis and ejected during the battle with the Ark. They were probably active for a while (1000 years or so) but being in the swamps of Borneo attracted little attention until the rest of the 'Cons woke up.

Now, the Constructions, that's a whole other can of worms. Personally, given how jacked up Season 3 was, I don't believe those are the actual Constructions building Megatron in Rodimus' Matrix trip. Call it Rodimus interpreting what the Matrix showed him if you like. Given that, what Omega told Prime works: they were Autobots (or at least neutrals) on Cybertron, got reprogrammed, were placed on the Nemesis as personality components, and Megs finally built new body shells just prior to 'Heavy Metal War'. The rest is history.

The Constructicons... won't touch with a ten-foot pole.

Insecticons, though. Megatron outright states in their debut episode that they're from the Nemesis when it crashed four million years ago. They were probably just crew that stayed behind to monitor things.

Well, after all, in the "Matrix sequence" we can see MORE than 6 Constructicons "building" Megatron (they are actually eight), so it's safe to assume there was a whole branch of "neutral" or "affiliated" Constructicons on Cybertron, sort of "ethnic group" --- and not just the (in)famous 6 Autobots-turned-into-Decepticons able to combine into DEVASTATOR.

I agree with the Insecticons point.

Thank you, I was so disappointed this board looked deserted.