I wish that I were able to wave a magic wand and give you an exact time-frame for when your infestation will be completely eradicated, but alas, it is not so simple. Thus, I implore you to answer the following queries to the best of your abilities. Doing so will allow the situation to be properly deduced.
- Is it pantry moths that you are seeing (and not a clothing moth)?
- How long have you been seeing pantry moths in your house?
- Do you believe that there is one primary source of infestation? Or could there be multiple?
- How many moths are you seeing on a day-to-day basis?
The answers to these questions all contribute to the severity of your situation, which directly relates to how long it’ll take to get rid of these flying nuisances.
Let’s first look at the life cycle of the pantry moth -specifically the lengths of time for each stage- to better understand how long a pantry moth infestation could last.
What is the life cycle of a pantry moth?
Pantry moths, or Indian meal moths, lay their eggs directly on or near the food source. A mature female may lay between 100 and 300 eggs at a time (with 300 being the average), though she can lay up to 500. These eggs are laid all at once or over the course of several weeks. After laying their fertilized eggs, the female moths die.
Larvae begin to hatch in approximately two to 14 days. Newly hatched larvae feed on grain while more mature larvae feed on grain germ. Depending on the food source, pantry moth larvae will take 14 to 40 days to fully develop.
Pocket Tip: Accidentally eating pantry moth larvae (or eggs) will not make you sick.
After the larvae are fully grown, they either spin a thin web and create a cocoon or are found lying out in the open. This stage, in which they are dormant, lasts around two weeks.
Pocket Tip: Quite frequently, the pantry moth larvae will go somewhere other than the food source to pupate, such as the crevice of a pantry shelf or the seam of a doorway.
The now non-disease-carrying adults have one sole purpose: find a mate and (if female) lay eggs. Males tend to perish soon after mating.
Pocket Tip: Adult pantry moths do not have mouths and, therefore, do not eat. (It is the larvae that do all of the damage.) Having the inability to feed also determines their adult length of life, which is around one to two weeks.
How long do moths live?
If you look at the calculations above, it appears quite simple. You read that a pantry moth is in the egg stage for around a week, followed by the larvae stage for approximately three weeks. From here, they enter the pupa stage for two weeks and then are just an adult for around a week. You quickly assess that a pantry moth’s life cycle is approximately seven weeks long.
I wish this were always the case.
Under very optimal conditions, a pantry moth can go through its entire life cycle—and thus live a very short (and very reproductive) life—in 28 days. In a less ideal environment, a life cycle can be as long as 300 days.
What other factors contribute to the time-length of a pantry moth’s lifespan?
There are other determining factors that must be considered:
- Was their food source abundant?
- What was the temperature in which they were living?
Pantry moth larvae eat a wide variety of foods (though not clothing) and can survive on very small amounts. An inadequate food source, though, will lengthen their developmental cycle, potentially keeping them in the larvae stage for up to 210 days. If the food source, such as a plastic bag of pasta or a cardboard box of cereal, is in abundance, they will quickly munch their way through their larva cycle. Being that they only grow to be 12 millimeters long (which is 6 quarters and 1 nickel stacked up on its side) and are quite thin, their dietary needs are small.
Pantry moth eggs and larvae prefer warmer temperatures. Their favored temperature is around 75 degrees Fahrenheit. Temperatures above 95 degrees Fahrenheit or below 60 degrees Fahrenheit significantly reduce the reproduction and survival of the pest. Specifically: In the egg stage, if the temperature of their environment exceeds 77 degrees Fahrenheit, it can cause a delay in hatching. In the early larval stage, if the temperature is below 68 degrees Fahrenheit, it can cause a lengthening of this stage. Larvae are inactive at temperatures below 40 degrees Fahrenheit.
How long does it really take to get rid of pantry moths?
Taking the above information into consideration, it can take anywhere from a week or two to six months to get rid of a pantry moth infestation. If, when seeing a single moth in your home, you immediately whack it (or spray it with our non-toxic Six Feet Under, whose sample size you could use on your bookshelf) and then sniff out and rid yourself of the source of your infestation, you’re nearly there. You’ll just have to contend with other flying moths, place several Pantry Moth Traps around your pantry and areas where the infestation was sourced to attract and kill those pheromone-chasing males, and then meticulously clean (and then clean again) your pantry, using Six Feet Under on all shelves and crevices to ensure that you’ve removed all eggs before they hatch.
A very short-term problem (and quick getting-rid-of resolution) is possible for very meticulous, thorough and conscientious cleaners. For the rest of us, though, that feel that we juggle too many balls simultaneously and have to also think about our pets, our hectic day-to-day schedules, and that evening’s dinner, it may take slightly longer. After all, you are attempting to clean every single intricate crack and crevice that pantry moth eggs could be laid in, which is no small feat, and, in doing so, stay on top of their (potentially) short life-cycle.
Perhaps I make the whole process sound too simple. On one hand, it is simple, as it’s a matter of following certain sequential steps. On the other hand, it takes a great deal of patience and perseverance. I recommend listening to a good book: Have you heard of Life on a Little Known Planet by Howard Ensign Evans, a classic book on natural history (aka insects) at its best, or For Love of Insects, a memoir by Thomas Eisner? You could plug yourself into an audio version of either text, temporarily forgetting the problem at hand, and remember that we at Dr. Killigan’s are just a chat, a phone call, or a message away.
Pocket Tip: If you’ve had a pretty bad infestation, hold off on restocking your pantry (beyond what you need short-term) until you’ve ensured that all eggs and larvae are completely gone. Remember that larvae need food to survive. If the food is gone, there is no survival.