The arachnid menace is coming at you in full force on the hostile planets of Starship Troopers: Extermination. They may have the numbers, but you have the highly advanced weaponry of the human race and a solid team behind you.
None of that is much use if you don't know what you're fighting. You might as well take a look at what enemies you'll be facing on the front lines of the war against the alien menace. With a little training, you may even come home with a medal. Just remember: the only good bug is a dead bug.
Drones
The weakest of the arachnid forces, they are still large and more than capable of killing you if you let your guard down.
These normally don't stray too far from their homes. But, if you stray too close to a nest, then prepare to potentially get overrun. They aren't too stressful one-on-one or at range, but if they have the chance to gang up on you, you'll definitely be in a tough spot. This is doubly so if they're bolstered by the deadlier cohorts of theirs.
Scouting ahead and clearing out the majority at long to medium range is the best idea when facing off against Drones. Just make sure not to get cocky and go lone-wolf. The bugs' strength is definitely in numbers.
Warriors
The bulwark of the arachnid army. Their sharp pincers and strong legs can tear apart a human Marine in mere seconds. So fight wisely. They can be deadly alone, but their bloodlust really comes out in groups. The Bulwarks should focus on keeping their numbers as low as possible with their SAW while backed up by the other classes.
They only have melee attacks, so like with most other arachnids, try not to let them get close. Use explosives like Thermo Charges and Proximity Mines to thin out the crowds without using too much ammo. Staying behind the walls and near ammo resupplies is a solid choice when you're getting overrun and don't need to run out for an objective.
Gunners
The only long-range threat to an individual Marine. Gunners are incredibly deadly, spitting toxic substances at your team over long distances.
It doesn't take long for a Gunner to take down a whole group of Marines before you even know they're there. Knowing that, communicate on your mic (if available) the moment you see one, or better yet, mark them with the Morita.
These will be priority targets for your Operators who can have long-range duels with them, or for experienced hunters who can use their jetpacks to flank them. They aren't as heavily armored as some of the deadlier bugs, but they are far from a glass cannon, either. They definitely take priority over Drones and Warriors.
Plasma Grenadiers
An important target, the Plasma Grenadiers may not be directly deadly, but they shoot ranged explosives at your teams' buildings and constructs.
You definitely don't want your walls, ammo supplies, or even objective destroyed by one of these things. So pay attention when they show up. They often stay away from the front lines, so sending your Operators and Hunters to take out these units is a solid strategy, as long as your team backs them up.
They have no attack other than lobbing their plasma balls, so don't worry about how they'll react, as they will usually be focused on destroying constructs. Don't leave yourself open to attacks from other bugs, though. Traveling away from the front lines in groups of three or more is ideal.
Tiger Elites
The deadliest of the arachnids by far. You'll need the skills of your whole team to take down these foes. Make sure you're doing your part.
There are practically boss fights for this game and should be treated as such. If you see one of these coming from far off, mark them or tell your squad. You should start whittling away at them from as far away as possible. It is surprising how easily they can take out multiple members of your team with just a few swipes of their scythe-like arms, even on walls.
Any explosives you or your team should be focused on trying to crack the Tiger Elite's armor. Marines with rocket launchers should definitely stop what they're doing and make their way to start fighting off these potent foes.
Other than that, it's all a game of numbers and skills. Make sure you're getting as many of your fellow Marines to fight with you to make the fight shorter (and less gruesome). Keep in mind what class you are playing as, and use your tools to their fullest ability. This may seem obvious, but when facing these deadly bugs, it can be surprising to remember you have a jetpack you could have been using this whole time.