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Major North American cities are full of large cockroaches. Given their numbers and relatively short lifespan, there must be staggering quantities of cockroaches dying in a city every day. However, I never seem to encounter their carcasses in cities.

I notice a fair number of dead roaches indoors, which actually surprises me since you would think that there is more thorough cleaning and pest control indoors vs. city streets. The number of dead roaches I see indoors seems about consistent with the number of live ones.

However, outdoors I see a lot of live roaches, and hardly any dead ones. Most carcasses I notice are mechanically damaged and near heavy traffic areas, so most likely stepped on by someone who was walking by. But what about roaches dying of natural causes (or disease/poison)? Are there animals that scavenge the carcasses very efficiently (ants? birds?)? Do the roaches like to run away and die in isolation? Do they just not die naturally very often, and usually get hunted by a predator?

Note that I am asking specifically about city cockroaches, in mostly concrete areas.

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    $\begingroup$ Ants pretty much scavenge everything. I don't know about North America but in India ants do a good job in finishing off dead/semi-dead cockroaches. :P $\endgroup$ – WYSIWYG Jun 14 '17 at 4:39
  • $\begingroup$ I have found cockroaches live around places of low temperature, like water reservoir at my place. The huge number of outdoor cockroaches you mention of might live around underground drainage system, far from the the path you commute. $\endgroup$ – Tyto alba Jun 14 '17 at 7:19
  • $\begingroup$ I looked up Wikipedia, according to it they need moisture and not low temperature. $\endgroup$ – Tyto alba Jun 14 '17 at 7:45
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In the big cities of North America (e.g N.Y), the big piles of dirt and moisture attract many hostile animals such as the ones you mentioned: the cockroaches. You should also consider that in the north there is a very common factor that attracts collonies of cockroaches: the low to mediocre temperatures. Moreover, you should reconsider the cleanliness of the sewers. The sewer and the leftovers that exist there are highly nutritional for the cockroaches. That's why you don't see many dead ones on the streets. And where is the start of the sewers? The sewers start from every house. That's why you notice more roaches in the houses than outdoors. They need a place that might provide them the sewer's environment such as the bathrooms, or an other place in the house that has moisture and is mostly dark. Cockroaches live and die to the same place and don't go somewhere else to die. The decay rate outdoors is higher of course, than indoors because every house is cleaner than the roads. With the process of cleaning many factors, such as mites are swept away to the environment.

For the second part of your question:

Outdoors there are many scavengers and natural predators for the cockroaches. Some of them are: toads, frogs, beetles, geckos, iguanas and birds. Entomopathogenic fungi have also been identified as lethal to roaches, as their spores attach to insects and kill them within weeks. Cockroaches affected by fungi then pass the parasite on to other cockroaches, and the cycle continues.

Ants prey on some cockroach species, but other roachess actually live with ants in their colonies. These are called myrmecophiles, meaning lovers of ants. They don't seem to offer their hosts anything in return for living with them, and are usually tiny and unobtrusive. Other species - termitophiles - live in similar fashion with termites.

And yes ants are the major factor of dicomposion in nature, because they devour almost anything.

I hope this answered your question, becaused I used very extended research :)

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    $\begingroup$ This is a good attempt at an answer! It would even be better (and attract upvotes) if you added some references to the research you used. $\endgroup$ – RHA Jun 14 '17 at 20:32

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