Zerg 101: Production-Income Matching, Part 1 - Larva production

This post will detail how larva production works, what role it serves in the Zerg economy, and why managing larva is a fundamental skill when playing Zerg.

One of the beating hearts of Starcraft and of RTS generally is production efficiency.  If it were just about the big picture decisions and then army control then there would be more tools to do things automatically.  Needing to manually control your production is an important part of the game.

The first part of this is setting an income level.  A mineral patch can be mined optimally by 2 workers, and a standard base therefore needs 16 workers to mine optimally.

This generates about 900 minerals per minute.  Terran can get more with mules but we're not Terran.

This income is then spent on production, tech and upgrades, and/or economy.  Unspent money goes into the bank, and the bank can be used to spend from in the future.

This post will focus on production because Zerg production is different in interesting and important ways, but let's keep talking about Terran just a little longer as the generic case.  Because production efficiency is crucial, we want to maximize that.  Optimal production means having enough production facilities to exactly spend your income if those facilities are operating all the time.  Too many production facilities and you will still spend your income but some facilities will be idle some of the time. The money used for those idle facilities could have been used on something else with no reduction in output.  Too few production facilities and you will not be able to spend your income.  The money in your bank then represents output that could have been realized.

So money piling up in your bank is one indication of inefficiency, and idle production capacity is another.  Only by matching your production capacity (and other spending) to your income can you avoid both of these.  This maximizes your output, which maximizes your army size, and armies win games.

In a simple example, one base without mules generates enough income to power 5 barracks with no add-ons producing marines as well as the supply depot production to support them.  More barracks than that and you can't use them all, fewer and you can't spend all of your money while just making marines and an appropriate number of depots.

I'm only illustrating a point here, don't go 1-base 5 rax.

Zerg needs to manage a similar concern but Zerg production is not based on how many barracks, factories etc. they have, but on a larva economy.  We're going to stop looking at Terran stuff now.

Larva are produced from hatcheries.

Hello, beautiful.

They produce naturally at a rate of 1 per 11 seconds, and the Queen's Spawn Larva ability will cause the hatchery to produce an additional 3 larva after a delay of 29 seconds.  She will have enough energy to do this (25 energy) every 31-32 seconds.  We can round a little and say that a Hatchery paired with a Queen will produce up to 6 larva every 30 seconds.  Twice as much as the Hatchery alone.

Now we're talkin'.

Once a hatchery has 3 larva on the ground its natural larva production will cease until there are fewer than that.  The Queen's spell, Spawn Larva (commonly known as "inject"), will still work beyond that but total larva production for the Hatchery is halved at that point since only the inject is working.  A hatchery cannot have more than 19 larva on the ground, and achieving this requires a lot of injecting without spending the larva for an extended time.  The Queen's inject is not autocast, the player must remember to do this every 30-ish seconds or larva output will suffer.  The player must also spend larva promptly to avoid having 3 on the ground for any length of time or larva output will suffer.

Larva can then be turned into any Zerg unit except Queens and the few that morph from existing units.  Drones and Overlords, which are your workers and supply, are also made from larva.  The morph time of a particular unit from larva may vary, with fancier units taking longer, but the larva output is not impacted by this, so the Zerg production cycle or "macro cycle" runs on these 30 second intervals like clockwork no matter what the player is producing.  All of this makes production as Zerg radically different from the other two races.

Zerg production throughput looks like this:

Flooding zerglings is always legitimate.

1 base income produces about 450 minerals in 30 seconds, 2 hatches with one of them injected produces 9 larva in about that time if operated efficiently, and these 9 larva can be morphed into 1 overlord for 100 minerals and the remaining 350 minerals can morph 7 more larva into pairs of zerglings.  On paper with our rounded numbers there is one larva remaining but remember that the larva production cycle is more like 33 seconds so it really works out closer to having enough to morph all 8 into 16 zerglings which take up exactly an overlord worth of supply.  So that's pretty efficient.

A couple things to note about this:

1. Zerg doesn't get a production queue in general, so you cannot achieve perfect 100% utilization of your production capacity by having another unit in the queue that begins building as soon as the previous finishes.  
2. Being late on your injects or allowing more than 3 larva to squirm around on the ground for any amount of time effectively reduces your production capacity.  If you do both of these things wrong at once larva production will completely stop.  Your Zerg equivalent of having 5 barracks can turn into effectively having 3, 2, or zero barracks if you do not stay on top of managing your larva economy.
3. After letting your larva production go idle it may not feel bad because when you go to make units you will have lots of larva on the ground waiting and be able to immediately make stuff!  But remember that larva production has been lost and cannot be recovered.  Train yourself to recoil from having larva on the ground idle or inject Queens standing around with more than 25 energy.
4. We have 1 base of income but a 2nd hatchery just for production. This can be built at an expansion or it can be built in your existing base.  An additional in-base hatchery for larva production is called a "macro hatch".

This is harder for new players to grasp but zerg production also has strong advantages and is in some ways easier to manage once mastered.  If you like Zerg don't be scared off by it.

Finally, Queen injects can be queued on the hatchery.  The production output doesn't stack but it does make it so that as soon as one inject completes the next will begin with perfect efficiency.  The net effect of this is to limit the damage done by forgetting injects.  If you are 10 seconds late on an inject you lose 10 seconds of larva production.  But you will be able to put the next inject on 10 seconds before this one expires or any time up to when it expires without losing any further time.  So you lost 10 seconds but now you have a 10 second margin of error.  If you are at some future time 20 more seconds late beyond that margin you will lose another 20 seconds of larva production and the Queen will now have enough energy to put a double inject on, giving you a full 30 second margin of error in the future.  It's still bad to miss injects, but this does limit the damage somewhat.  You can read about different inject methods here. I'd recommend starting with the Base-Cam/Manual method.

Larva are most crucial in the early game when you are starved for production capacity.  Later, as you expand and have more hatcheries and begin to build more expensive units that still only use 1 larva your larva economy will become less critical.  But during the early game managing this optimally is one of the most important things you can do as Zerg.

If you haven't been doing this well and you improve that aspect of your play it will completely transform how Zerg feels.

There are other interesting implications of larva, including:

• Economy vs army
• Rapid tech switching
• Your mineral gas mixture and tech choices will impact your larva needs
• Rapid reinforcement with fast morphing units
• Zerg production being based on hatcheries changes our expansion patterns.

But these are all topics for other posts.

GLHF!