TODAY | September 07, 2013
>> every day feel.
>> it is so gross.
>> reporter: in oklahoma towns, it happens every year and is a mess as thousands and thousands of crickets pile up and hang off walls and windows of homes and businesses.
>> after awhile, they die.
>> reporter: people may not like it, it's natural for all the crickets who this time of year have one thing to do.
>> they are looking for a mate so there can be more crickets next year.
>> reporter: the signal to gather and mate comes from the change of season and the weather, which this year, dry in the spring and wet in the summer was just right.
>> it's fall, the nights are getting cooler. this year may be worse than others. it's nice and humid. it's good for crickets.
>> it's good for business if you are an exterminator. calls for service are coming in. exterminators found enough crickets to fill a 30 pound bag. while people aren't happy, the rest of the animal kingdom is having a feast.
>> birds eat them, frogs, lizards, small mammals. they are protein packs for animals.
>> reporter: better news, this plague won't last forever. when the weather gets colder, they will all be gone until the new generation comes to town next year. for "today," mark potter , nbc news.