Q. We’ve had a problem with cockroaches. I don’t know if I’m seeing the same cockroaches that I started with or if these are new ones. How long do insects live anyway?

A. Some insects only live for hours; some insects live for years! There’s a huge range in life expectancy from one insect species to another. A German cockroach can live from 3 to 6 months (unless it meets up with an effective pesticide, or a predator, or a shoe!).

Some adult insects live only long enough to mate and start the next generation. A mayfly, for example, is so short-lived that it doesn’t even have functional mouthparts! What’s the point in feeding when you only live for a day. Mayflies emerge or “hatch” together in large swarms so they don’t have to waste time looking for a mate.

Many insects don’t live long as adults but may have a very long development period as immature larvae or nymphs. The periodical cicada holds the insect development record. A cicada nymph lives and develops in the ground for anywhere from 13 to 17 years before it emerges as an adult destined to live only 30 days.

The life cycle of developing insects can be slowed down or speeded up depending on temperature, humidity, day length, and the amount or quality of food available. The time to maturity under “ideal conditions” may be much faster than if conditions are less than ideal. For example, a silverfish can develop from egg to adult in 3 months in a warm temperature with a high humidity. But if conditions are unfavorable, development to adult can take as long as 3 years.

When conditions get really bad, some insects go into diapause, a kind of suspended animation, until things get better. Fleas can insert a sort of time-out into their life cycle if there is no animal around to feed on. For instance, if a family goes on vacation for a month and boards the dog, fleas left behind in the home will simply wait in the pupal stage until they again detect the presence of a warm-blooded animal to feed on. Usually insect diapause lasts weeks or months, but in rare cases has lasted years.

Here’s the average adult lifespan of some of our common insect pests:

·       fruit fly – 1 month

·       carpet beetle – 1 to 2 months

·       termite queen – 30 years

·       German cockroach – 3 to 6 months

·       house fly – 15 to 25 days

·       Indianmeal moth – 5 to 13 days

·       powderpost beetle – 14 days

·       midge  –  hours

·       mosquito – 1 to 3 months

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