What we want to avoid 1) overturned lids

West Chester Borough ordinances require waterproof lids on trashcans:

§ 62-3 Disposal regulations…F

Rubbish or refuse shall be stored and placed out for collection in waterproof metal or plastic containers with handles which shall not exceed a capacity of 35 gallons. All containers shall be provided with tight-fitting lids which are windproof, ratproof and flyproof. The lid shall not, however, be roped, chained or permanently affixed to the container unless hinged by the factory. All containers must contain the street address of the owner in clear, legible and conspicuous writing on the outside of the container. Any garbage, rubbish or refuse that is not contained and/or placed in a waterproof metal or plastic container with handles not exceeding a capacity of 35 gallons or in a disposal bag will not be collected by the Borough.

If lids are missing, water can accumulate in the open trash container unless it has holes drilled in the bottom. And furthermore, even if the can is turned over, an unattended lid can gather water and host mosquito larvae:

Trash can lid with larvae

The mosquito life cycle

CDC life cycle

Life cycle description from the EPA:

All mosquito species go through four distinct stages during their life cycle:

egg – hatches when exposed to water
larva – (plural: larvae) “wriggler” lives in water; molts several times; most species surface to breathe air
pupa – (plural: pupae) “tumbler” does not feed; stage just before emerging as adult
adult – flies short time after emerging and after its body parts have hardened.

The first three stages occur in water, but the adult is an active flying insect. Only the female mosquito bites and feeds on the blood of humans or other animals.

After she obtains a blood meal, the female mosquito lays the eggs directly on or near water, soil and at the base of some plants in places that may fill with water. The eggs can survive dry conditions for a few months.

The eggs hatch in water and a mosquito larva or “wriggler” emerges. The length of time to hatch depends on water temperature, food and type of mosquito.

The larva lives in the water, feeds and develops into the third stage of the life cycle called, a pupa or “tumbler.” The pupa also lives in the water but no longer feeds.

Finally, the mosquito emerges from the pupal case after two days to a week in the pupal stage.

The life cycle typically takes up two weeks, but depending on conditions, it can range from 4 days to as long as a month.

The adult mosquito emerges onto the water’s surface and flies away, ready to begin its life cycle.