I would find Death Rattle to be annoying in play (much like I find Dragonfear to be annoying). Bunch of attack rolls you have to resolve, for some hard to track/remember conditions, on a power that can be used every encounter.
From a design perspective, either make it an auto condition, or make it a fire and forget power if it's going to require to hit rolls. Option one, close burst 2 effect, creatures in burst are slowed until eont (no attack roll). Option two, close burst 2 attack, creatures in burst, 1/2/3d6+Stat thunder damage. Make it either easier to track, or easier to resolve. Fluffwise, I have a difficult time seeing how this power would only effect enemies.
Resilience of the X mechanics seem backwards. Beetle should apply to the +2 Con option, Dreadful should apply to the +2 Cha option. Also for Resilience of the Dreadful, instead of never granting CA vs Will (something one has to remember), why not just give +1 Will (something to bake in and forget). Resilience of the Beetle is good, it's already baked in.
Chitin is an ignorable combat feature for as little as it is likely to come into play. I'd either ditch it, or perhaps better, convert it to some adventuring aspect, like they can comfortably sleep in heavy armor, and do not take a penalty to endurance and constitution checks for wearing armor or shield.
Feats are nice conceptually, but they might be low on the totem pole mechanically. Characters are so feat starved these days, only the "best of" racial support makes it onto my radar. First of all, I'd be tempted to take the cheap way out and add another feature that says "You are considered to be from the thri-kreen family, and qualify for feats and paragon paths that have thr-kreen as a requirement. This would open up a few nice doors right away. Then I'd add some unique feats. Conceptually I like the feat names War Drone and Dread Carapace. I'd change them up a bit, and add some more. For the sake of throwing some random examples (because it's fun, and comes with the caveat not a whole lot of thought went into these)...
War Drone [Racial]
You are used to working with others and providing them constant assistance.
Requires: Trox, Leader
Benefit: Adjacent allies gain +1 bonus to melee attack rolls.
Dread Carapace [Racial]
You have painted and scarred your hide to make yourself more intimidating, and increase the potency of your rattle.
Requires: Trox, level 11+, training in intimidate
Benefit: When you make an intimidate check you roll twice and use the better result. Additionally you gain a +1 bonus to all defenses against attacks from bloodied enemies.
Hardened Chitin [Racial]
Your chitin has transformed into an even harder protective shell.
Requires: Trox, level 11+
Benefit: You gain resist 2 all against melee and ranged attacks. This resistance increases to 4 at level 21.
Predatory Senses [Racial]
Your sense extend to the spirit realm.
Requires: Trox, primal power source
Benefit: You cannot be surprised. You also gain a +2 feat bonus to perception and initiative.
One good way to make racial feats is to look at existing feats that are not used very often because they just need a little extra umph, and add something to them. Good luck, and hope you can entice a player to play your race.