Pest Management Professional • November 2022 • Tips & Tricks

Dealing with a stored product pest (SPP) problem in a home or structure sometimes calls for a healthy dose of patience. In many cases, getting all the necessary information from the customer to perform a thorough inspection can be a challenge.

To really solve this problem, all sources supporting the infestation need to be located, identified and eliminated. Additionally, knowing the species of the pest will give you key clues to its behaviors, biology, preferences and habits. Here are a few tips to keep in mind:

⦁ Think beyond the kitchen. Food and feed can be found stored in closets, basements and garages. On some occasions, a customer can forget they’re even there. Also, it’s not uncommon for snacks to be kept and eaten in game rooms and home offices.

⦁ Find out where the dog food, pet treats and bird seed are stored. These items are not always the first to come to mind when asking the customer “Where do you keep your food?”

⦁ Inspect all items made of plant and animal material. This includes decorative pieces, dried flower or plant arrangements, and craft items/children’s art projects that contain beans, seeds or noodles. Items of sentimental value can be placed in a freezer, as exposure to extreme cold can eliminate the infestation.

Getting to the bottom of an SPP infestation source requires us to get really good at asking questions, which can make the process feel more like an investigation rather than an inspection.

The sawtoothed grain beetle (Oryzaephilus surinamensis, aka STGB) is one of the most common SPP that pest management professionals (PMPs) will encounter in both residential and commercial accounts. Its common name comes from the sawtooth-like projections on each side of the thorax. Measuring about 0.10 of an inch long and dark reddish-brown in color, STGB can infest just about any dried food product, including dried fruits, cereals, rice, flour and other processed foods. It is often found infesting rodent baits, bird seed and chocolate.

STGB easily invades packaged foods through openings as small as 0.03 of an inch. They do not, however, chew their way through packaging material. When identifying the pest, note that merchant grain beetles (O. mercator) are very similar in appearance to STGB but are capable of flight; STGB is not known to fly.

In most cases, control is identical to the steps taken for all grain beetle infestations in residential and light commercial facilities. First, inspect, locate and dispose of all infested materials. Second, deep-clean the infested areas thoroughly. Third, a crack-and-crevice treatment with an effective residual insecticide should be made to shelving and voids where the infested materials were stored.

For proper identification of SPP, it’s imperative to be able to distinguish the feeding habits of the four main groups: internal feeders, external feeders, scavengers and secondary pests. This will help you properly identify the species, develop an integrated pest management (IPM) plan and communicate the plan to the client.

Inspection is critical. It must include the investigation of all individual packages of potential harborages, such as grains, cereals and raw legumes. Infested material must be disposed of immediately and properly. In some cases, the infested material can be placed in the freezer — for an appropriate length of time — to eliminate the active infestation.

Pheromone traps can tell you the density and help pinpoint the location of the infestation. If necessary, use a non-residual aerosol labeled for use in and around food to flush out flying SPP. Use residual insecticides per label instructions, and carefully treat cracks and crevices in the infested areas.

When used in conjunction with insecticides, regularly scheduled insect growth regulator (IGR) treatments within a commercial food facility can provide additional protection against SPP that might be overlooked in low-level infestations. Many times, IGRs are viewed as more account-friendly by customers, and require less preparation or cleanup after application.

Keep in mind, however, that most labeled IGRs are intended only to prevent growth within SPP populations, not kill. And in some cases, you may not want to stop the growth at certain life stages, to decrease the amount of damage caused.

The bottom line? While IGRs are not a silver bullet, they can be a critical piece of any successful program in large food-production and other areas prone to SPP infestations.

Dealing with SPP can be tricky, especially in a food-production or -processing environment. While sanitation and removal of infested products are the primary ways to achieve long-term control, there are situations that require chemical control tactics. For example, if a shipment of infested product is inadvertently accepted and there is an audit coming up, it may be necessary to fog so as to knock down the adults to meet third-party auditing requirements.

Fogging applications also may be made regularly based on factors such as time of year, processing of certain commodities, or on pheromone trap catch data. It is important to consider the characteristics of the material you are fogging with, however, and the expected outcome of the application. Some fogging products are designed to provide quick knockdown and nothing more. Others contain ingredients with longer residuals and may be used as part of a preventive approach.

SPP know where to find the “good stuff” in any home or commercial kitchen. That’s why they often invade areas in the kitchen where food is typically stored. Nobody wants to be greeted by these unwelcome visitors when they open up their pantry or cabinet, so give customers these three steps for prevention:

1 Seal food containers and store items separately, while keeping tabs on expiration dates and discarding food items as they age.

2 Deep-clean areas around appliances on a regular basis, as crumbs can accumulate and attract insects — not only SPP, but ants and other pests. Also, be sure to seal any cracks and crevices around countertops to prevent the buildup of food.

3 Ensure food is stored in temperature-controlled rooms, as it can accumulate moisture if not stored properly, creating an ideal habitat for insects. This goes for pet food and birdseed, too.

SPP like “pantry” beetles and moths can be challenging in residential accounts. It can be as easy as finding the infested dog food, birdseed or grain products in the pantry or garage and eliminating it. But other times, the source may not be easy to locate or access.

Old rodent bait in a hidden area can be a culprit. So can grain products that may have spilled into a void area that isn’t easy or obvious to locate. Depending on the pest, ask homeowners whether they have any collectible items such as furs, skins, taxidermy, dried flowers, etc.

Care should be taken with pheromone traps, particularly with Plodia and Ephestia moths. The sex pheromone for these two genera is typically potent enough to lure insects in from outside. In commercial environments, they generally are labeled to be placed 25 to 50 feet from doorways. It is difficult to get that far from a window or door in a residential home, however, and this will require some homeowner education if they’ve purchased these traps themselves.

One last tip: Silica dust is a great option for treating voids under cabinets and inside walls, hard-to-reach areas, cracks and crevices in cupboards and closets, and other labeled areas to provide long-lasting protection against SPP.

Some of craziest SPP-infested materials I’ve encountered as a PMP include a random cereal box on a garage shelf, cat food under the fridge, bagel flour buildup under bakery ovens, a Christmas wreath inside a hope chest in the living room, and my favorite: a decorative loaf of shellacked bread on a kitchen shelf. I am sure you have your favorites, too!

You know that finding the source for the moths, mites and maggots (oh my!), as well as beetles and other SPP is the key to shutting them down. In most cases, these situations also require using an appropriately labeled adulticide to get control.

My recommendation is to choose a labeled aerosol or concentrate that controls insects quickly, so surfaces can be wiped without worry of unwanted residue. Customers also appreciate formulations that are exempt from the U.S. Environmental Product Agency’s Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) 25(b).

Just when your customers think that throwing out an infested bag of popcorn did the trick in controlling an SPP infestation — they find more the next morning in the cereal box.

Why are these pests such stubborn opponents? In addition to their ability to hide in small cracks and corners where they can be easily missed, people mistakenly tend to think these annoyingly tenacious invaders can’t spread beyond the pantry into the rest of the house.

In reality, some of the species that commonly invade pantries can survive in almost any dark, moist environment where mold is likely to grow. Breaking into sealed packages of stored products simply gives them an abundance of food upon which to thrive.

Booklice (Liposcelididae), for example, are typically found in books and stacks of paper. But they may spread into stored goods. Other pests like carpet beetles (Anthrenus verbasci) and cigarette beetles (Lasioderma serricorne) also may originate in the pantry.

That’s why it is recommended to conduct a wider search and apply an effective insecticide in other areas of the house after your customers clean out their pantries.

It is often incorrectly assumed that SPP are only those insects that might get into the dried food goods in your pantry. In reality, the term “stored product pest” refers to insects that infest both food and non-food materials made from plant or animal origin.

When you think about it, that list of materials comprises a whole lot of things. The reason SPP are important is because we humans like to store a whole lot of things — from dried seeds, grains, spices, cereals and pasta to wools, feathers, furs, hair and hide, from wooden furniture to picture frames, and much more. Humans love to store things we find valuable, and this group of pests loves to eat what we store.

SPP don’t care whether their food sources are in a food plant, a distribution warehouse, or a residence. If you store it, they will eat it. This confirms to us that Indianmeal moths, flour beetles, grain beetles and weevils are, of course, SPP, but so are carpet beetles, clothes moths and powderpost beetles, along with a long list of other insects that eat these materials.

So, as you read through this month’s Tips and Tricks section, know that these suggestions will not only help your customers in their homes and workplaces, but also will help protect those items that you find valuable enough to stash away in your kitchen or other living areas in your own home.

SPP are tropical in nature and very dependent on temperature – they like it warm, typically 70 degrees Fahrenheit or warmer. As winter approaches and the weather gets colder, we tend to think our insect pest populations will be less active. This is true for insects making their way in from the exterior, but SPP live in the food we store. Often, there are interior populations that exist during colder seasons. If we’re storing our food in areas that maintain warm, comfortable temperatures, SPP are still very much a concern. In fact, many dry food-processing facilities see an uptick in SPP activity in the winter, many times thriving in heated areas that are not part of the regular sanitation schedule. Monitoring for SPP year-round helps ensure pest populations do not go unnoticed until the spring.

As PMPs, we monitor SPP movement as they move out of one facility, in-transit to another, and then move in and take up “pestidence.” One method of limiting “pestidence” is through organizational cleaning and applied product rotation. The standards of practice include first in, first out (FIFO); last in, first out (LIFO); and first expired, first out (FEFO).

Like the gastroenterology of people, the trash coming out of the back of a facility can tell a lot about how things come through the facility. Consider yourself a facility “trashologist” by routinely examining the method of trash-handling, the quantity of trash, the type of trash, the trash content and the trash odor. These and other factors can provide significant clues to the root causes of poor product rotation and probable pestiferousness.

Don’t let “pestidence” take precedence. Waste can be evidence of haste. Glean from garbage. There’s cash in trash!

After you identify an SPP infestation, get familiar with the basic biology of the specific insect at hand.

For example, let’s say you identify an infestation of Indianmeal moths (Plodia interpunctella, or IMM) in rice in a warehouse. You have the client remove the contaminated product and clean under the racks. Problem solved, right? I mean, you did find the source.

But you also know that IMM larvae will wander — sometimes great distances — to enter their pupation cycle. Did those larvae relocate to an area not cleaned or treated? Once pupation is over, adults are going to emerge. It could take a few weeks, maybe even months. And once they emerge, they’re going to mate. Those newly mated females are going to look for any food product to deposit their precious fertilized eggs. Will another new bag of rice be chosen? This could be a bad look, if you overlook this key part of IMM biology.