By: Dr. William H. Robinson
As an online “Dear Abby” for homeowners and their pest problems, I have come across a couple letters that go like this:
Dear Dr. Robinson,
This morning, I found little, white larvae-like, crawly things all over my kitchen floor. I thought they might be maggots because I had chicken bones in the garbage…
Dear Dr. Robinson,
I have small moths about three-eighths of an inch long, and arrow-shaped when they are resting; and I have little white worms with a dark head in my cabinets, and crawling on the ceiling…
Both of these customers have Indianmeal moths. This is the one of the most common insects in stored food in households, and yet one of the most unrecognized of all pests. They are found throughout the country — and the world — in residential and commercial food stores. There are several generations a year, but they seem to be noticed more often in the fall and winter months.
The habits of the caterpillars and moths annoy homeowners. The full-grown caterpillars migrate a short distance (during the day) away from the infestation site before forming the pupa, and the moths fly (but not very well) in early evening. So, infestations are usually evident day and night by the presence of moths and caterpillars. There may be noticeable peaks in abundance, but generally, there are a few caterpillars or moths out all year.
However, the descriptions provided by homeowners are often a mix of useful and misleading information. For example, the caterpillars are often thought to be maggots (as in fly maggots), and at times Indianmeal moth caterpillars may be in kitchen locations that would otherwise have fly maggots. The link to the Indianmeal moth is the “dark head” on the caterpillar, and the fact that the critters are crawling on walls and the ceiling (something not done by maggots).
Moths do not always fly near the infestation, just as caterpillars move off the site. Moths may be fluttering in rooms away from the food source and, once separated from kitchens and pantry, they are often suspected as clothes moths. The link to an Indianmeal moth is the “arrow shape” and coloration that is half gray and half dark brown. Clothes moths are uniform gray and slender moths that don’t fly far or well from their infestation site.
Dear Dr. Robinson,
The pest management technician who came to spray said that the Indianmeal moths probably had built a nest somewhere. We cleaned out all our cabinets and pantry, but don’t see any type of nest…
This letter is a good example of how the wrong information can mislead and misdirect people and treatment efforts! The idea that all insects make “nests” is common—ants do it, so cockroaches must (wrong!); wasps do it, so flies must also (wrong!); and Indianmeal moths don’t do it! Large numbers of caterpillars may be on infested food, but it is not a nest. Also, by looking for an obvious nest site, infested food material may be overlooked. Technicians should be trained to be careful of what they say about an infestation. The wrong information can lead to continued frustration.
Treatment tips
What is the best treatment strategy? Like most household pests, finding the source is the key to success. For most residential and commercial sites, the source will be easily found—dry pet food, bird seed, cake mix, chocolate, dried fruit or a few forgotten pieces of Halloween or holiday candy. Sometimes, though, the food source is in the back of the cabinet (or clothes closet) in a box of cereal that shows no outward sign of being infested.
Keep in mind, it is not enough to find and remove the source. The site should be vacuumed to remove food debris and any stray caterpillars.
Even after all this, there may be some continued problems unless you explain some features of the life cycle. Moths live for about three weeks, and during that time they may fly about the house. They are usually active a few hours after sundown, and can be seen flying from wall to wall, and resting on walls and ceilings—generally making a pest of themselves, and making your service look bad! The infestation source and the caterpillars may be removed, but moths will remain. One or two pheromone-based sticky traps can help. Yes, they only attract males, but they can help to reduce the few moths that may linger after the clean-up.
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