Pest Prevention and Control Measures for Food Storage, by Elk H.

Friday, May 29, 2009

Something you may not have given much thought about in your planning for long term food storage is Pest Control. All the hard work, preparedness and money spent on stockpiling and storing food can be quickly ruined by pests. You need to protect your investment. As a former exterminator I have seen my share of these pests and can share my experience and knowledge of control measures. While some of these measures are just ordinary common sense, we all know that common sense isn't all that common.

A few things to consider:
Most infestations come home from the store with you. You would be surprised to learn what I've found in the average, clean looking big name grocery store!
Dry pet food is notorious for being infested. Pet food is not processed and packaged with the same standards as "people food".
90% of Stored Product Pest Control is not about chemical treatments. We will use poisons sparingly and effectively.
Some, but not all, pests are disease carrying.
While there are hundreds (or thousands!) of individual species of pests you could have to deal with, we will focus on the three main problem pests when it comes to Food Storage: Pantry Pests, Rodents and Cockroaches.

PANTRY PESTS
Pantry Pests generally include Moths, Beetles and Weevils. There are too many species to list individually, but luckily the identification, prevention and control measures are all similar enough to lump into one category. Most Pantry Pests have a similar mode of action: the adult bores a hole into the grain/kernel/meal, lays its egg and repeats. The larva hatches inside the grain/kernel/meal, then eats it's fill until ready to pupate. The pupa hatches out of the grain/kernel/meal as an adult, and the cycle repeats itself.
They usually appear after bringing home a product from the store that was already infested, however some indigenous species do infest crops, and so may infest the grain in the field first.
If you spot moths, beetles or other stored product pests in your home or food storage areas, it's already too late. As mentioned above, the adults are not what will be eating your food, it's the young inside your rice, corn or wheat that is destroying it. While it's fine to eradicate the adults you see, the real problem is in the food itself. Once cut off from the food source, the adults will die off without having reproduced.

Inspection
All stored product should be removed from storage and inspected for infestation. Do not skip over anything just because it's an unopened box or what you think is an airtight container, go through it all. You may see webbing (like flat spider webs) inside a heavily infested product. You might see active adults working to lay their eggs, or holes bored through packaging like waxed paper and plastic bags. If you can afford to, throw this infested product out. While not the most economical approach this is what most homeowners will do.

Sanitation and Exclusion
Once your cupboards are bare it's time to get cleaning. All cracks, crevices and corners should be vacuumed clean of dust, flour and food stuffs that may have fallen in. In absence of a vacuum, wipe out everything you can with a wet rag, then blow out the voids and repeat until as clean as possible. You can treat the cracks and crevices with a general purpose pesticide at this point if you like, but it is not necessary. The cracks and crevices should now be filled with caulk, or something similar. This serves the dual purpose of both sealing out future food spills and pests, and sealing in anything you may have missed.

Control
As mentioned above, throw out all known or suspected infested product if you possibly can. If that is not an option, there are things we can do to kill the critters inside without losing the grain. Please note that while these bugs might seem disgusting to us, and they are eating your food, you can eat them without adverse consequences as most are not disease carrying. How shall we cook them? Let's bake!
An oven set to 130 degrees for four hours is the minimum standard for killing the larvae and adults. No promises on the eggs as they can be extremely tough. A slightly higher heat and more time will likely net better results, but use caution not to damage the grain.
Freezing the grain can also kill the larva and adults, and again, no promises on the eggs. This method is not as effective as baking, and may be impractical.
A professional will use fumigation to treat a large amount of infested product, say a grain silo full of weevils, but it’s very expensive, and may not always be available to you. In any case, you can’t just go pick it up off the shelf, you need a Pest Control Operators License to purchase the chemical, and rightly so, it is highly toxic.

Storage
The packaging your food comes in from the grocery store is not good enough. These pests can bore a hole into the toughest shell nature can provide, do you think a cardboard box or waxed paper will stop them? Of course not. The best containers are glass or metal and airtight. Tupperware/Rubbermaid type containers are second best. Ziplocs and plastic bags are not acceptable for long term storage at all. It's not a bad idea to store bulk food in many small containers rather than one large one. Don't put all your eggs in one basket!
Finally...
Check your food stuffs regularly. Periods of dormancy are a part of an insect’s life cycle. Just because you don't see them now, that doesn't mean they're not there!

RODENTS
Mice and Rats are some of the most damaging creatures we have to deal with. They eat what we eat, live where we live and carry parasites like lice and fleas. Because they are very similar to us biologically (one reason they are used extensively in research laboratories) it is easy for them to transmit disease to humans.
Luckily, control is actually very simple.

Identification
The only important reason to differentiate between a rat and mouse problem, is to choose what trap to use. A rat trap is just too big to effectively kill mice (something akin to killing an ant with a sledgehammer), they sometimes completely miss the mouse, and mouse traps only serve to make the rats mad.
The telltale signs of mice and rats are holes chewed into objects and food packaging, droppings, odors and noise.
As with all rodents, both mice and rats have large incisors (front teeth) that never stop growing. Because of that fact, they must constantly chew anything and everything in order to keep them ground down (I've seen pictures of a rat, not allowed to chew at all in a laboratory, whose lower teeth grew up over his head and into his skull!). You may see two parallel scrape marks in some materials from these teeth, the size will tell you if it's a mouse or rat. They will chew electrical wiring, and are the cause of a surprising number of house fires (they are actually attracted to wiring because it looks and feels like one of their natural foods, grass shoots).

They both leave droppings wherever they go, black in color, tube shaped like a grain of rice. Mouse droppings are about the size of a grain of rice, and rat droppings are naturally bigger than that, about a half inch long by a quarter inch wide. Both species also urinate everywhere they go, and so will leave urine trails and odors behind.
A sound at night like someone scratching their nails lightly on the wall indicates a mouse problem. People with rats in their homes describe it as sounding like "elephants in the attic". You may not hear anything at all, though, and still have a problem with either pest, sounds are just an indication. Rats love to nest above the water heater and furnace where it's always warm, especially in winter. There is usually a screen vent above those appliances, where you may see nesting materials like candy wrappers and snail shells (a favorite food). Rats do, but mice do not drink water, they get all the moisture they need from their food.

You may mistake a baby rat for an adult mouse, you can tell the difference by the tail, a rats will be thicker and almost as long as its body. A baby rat will have very large feet as well, all ages of mice have small, delicate feet.

Exclusion
Exclusion is the first step. Seal any and all openings into the house. A rodent’s skull is the only solid part of his body, if he can squeeze his head through, he can flatten the rest of his body out to squeeze through, too. A mouse's head is about the size of a dime, or you're little finger. If you can fit a finger in a hole, seal it up. The smallest rats head is about the size of your thumb, but we're going to seal up all the holes we find anyway, right?
Check and seal all vents to the crawlspace, especially around the air conditioning tubing, with steel wool, expanding foam or other inedible material. Do likewise to the soffit (attic) vents. You don't have to make it bulletproof, just enough to discourage them. The bottom of a side garage door is almost guaranteed to be a problem, it's required building code -to allow carbon monoxide gas from cars to escape. While I would NEVER suggest you break the law or bypass any safety measure, some people install a weather-stripping door sweep to keep the mice and rats outside where they belong. Trim all tree limbs that overhang, or worse, touch the house, as this is the Roof Rats favored method of entry. Anyplace two roof lines come together, climb up and seal the gaps in the soffits. Clothes lines and the like should not be attached to the house in any way. Ensure that any fences or other structures don't come within several feet of the roof, rats are excellent jumpers. Think of squirrels, they are basically just cleaner rats with furry tails. Keep ground-cover, especially ivy, trimmed back from the house, at least 2 feet. Wood piles should not be stacked against the house, you're just inviting trouble. Check the entire footprint of the house for tunnels, Norway Rats like to tunnel in, I've found many getting in that way.
Rats and mice do not live exclusively in your home, they come and go as they please.
Once the structure is sealed up, one of two things has happened: You have sealed them out, or you have sealed them in. If you've sealed them out, great, you're done! If you've sealed them in, how should we get rid of them?

Trapping
Trapping is hands down the preferred method of killing them. There is no better mouse trap! The standard mouse and rat snap traps are exactly what you need, and they can be used over and over again. Use a very small amount of peanut butter underneath the trigger for best results. A big glob will soon dry up and a crafty rodent can just gently pick it off. Smear a little underneath, and he has to jump up there with both feet to dig at it and, well, you get the rest. An old trick is to use a wire twist tie to secure a nut or a snail to the trigger for an especially tricky rat. Both size traps should be slid in perpendicular to the wall (skinny end with the trigger goes against the wall), mice and rats both travel in straight lines against the wall (they use their whiskers to feel their way along in the dark). Trapping also insures that you control where the bodies will be for retrieval and disposal. You can place traps anywhere you've had activity that is convenient for you. The mice and rats sealed in will eventually get hungry enough to explore and find your trap, I promise.
Do not bother with live traps or glue traps, you risk getting bit and infected, and if released from a live trap they will probably just come back anyway.

Maintenance
Once you have stopped catching mice and rats, and you're very sure the problem is solved, then you can consider using baits (poisons) as a prevention measure. If a rodent somehow gets in later, he will take the bait, which are all slow acting (several days) and leave when he starts to get sick. Mice are small enough that they don't cause too many problems if they die in a wall, they just don’t have the body mass. Rats, on the other hand are horrible to deal with in a wall. If you don't follow my advice about trapping and go right to using a poison with a rat, I promise you will regret it, I've learned this the hard way. The stench of death (rotting meat in your walls), the brown goo leeching through the drywall, the flies and maggots will remind you of these words.
Be extremely careful using baits outdoors. In fact, I don't recommend it. There is nothing you can do to keep pests out of your yard, all you can control is the structure of the house. Most baits today are pretty safe, but I have had a customer kill her own dog by not following my advice and putting her own store bought bait under a wood shed. Can you imagine if a child had gotten into it? When a professional has to bait outdoors, he uses a tamper-proof metal or plastic box. These can be purchased if needed.
This last statement is going to upset some people, but cats are NOT the best rodent prevention and control measure. Yes they will kill mice and rats, and they can thin the herd, but they will never eradicate them all. Mice are a staple food to scores of predators like birds of prey and snakes, and the mice still manage to be the second most successful mammal on the planet! Have all the best mousers you like, they will help, but follow my advice above for best results.
And please, don’t leave pet food out at night! Keep dry pet food and the like in metal cans with tight fitting lids, and far from where you store your own food.

COCKROACHES
Cockroaches are filthy, disease-ridden creatures. All species thrive in unsanitary conditions. They breed incredibly fast, that's part of the problem. A male and female German Cockroach, given an ideal environment can produce 1,000,000 offspring in one year. They are typically brought home from somewhere else like the grocery store, in someone's luggage, etc.
In the old days they were extremely hard to get rid of, today, it's a piece of cake.

Identification
There are many species of cockroach, but we will gear our attack toward the German Cockroach, as he is the main culprit in ruining foodstuffs. Outdoor Roaches like the American or Oriental are not usually an infestation problem inside the house, they are just a nuisance.
The German Cockroach is about a 1/2 inch to 3/4 of an inch long. Tan or brown colored, usually with two distinct black parallel lines on its head. They will hide in cracks and crevices under a sink, in cabinets or the baseboards, behind wall paneling, etc. (in the wild, they live under rocks and tree bark). As with other pests, it's not a bad idea to fill these cracks and so eliminate their habitat. They will leave droppings that look something like black pepper, egg sacks after hatching, and their shells after they molt (shed their skin, so to speak). They avoid light, and will scatter for cover if you turn on a light while they're out.

Sanitation
Clean grease and spills thoroughly, especially under the stove, oven and sink. Be sure to clean all surfaces well, including the cracks and crevices. Keep your food in pest proof containers. Do not give these guys an inch. Without proper sanitation it is impossible to get rid of them, you must take away the food sources (clean up spills)!
Control
Do not bother with any kind of spray, use a Bait Gel. It's safer and much more effective, in fact, in my opinion it revolutionized the Pest Control Industry. It will come in a mini syringe with the active ingredient Hydramethylon. My experience is that it kills about 75% of a population in 2 weeks. Then 75% of what's left in another 2 week follow-up visit. After 6 weeks, I can call a job done. For contrast, using conventional sprays, I could kill about 10% of a population per visit, and slowly make ground on them over many months.

CONCLUSION
It would be wise to stock up on pesticides just as you would medications. They are just not something you can replicate yourself. None of these products are terribly expensive, you can probably pick up everything you need for about $100. Note that these products do have a shelf life, so use them or give them away before they expire, and replace as needed.
You can see that 90% of Pest Control is not about chemical warfare, it's about common sense and cleanliness.
Here's the top ten things I recommend you stock up on:
1. General Purpose Pesticide like Malathion or Diazinon. Try to find a "Wettable Powder", it keeps longer and can be mixed to whatever strength required. It also sticks better than liquids after application. In addition to a powder, try to find a Granular product, it is applied with a seed spreader and activated by water.
2. Ant Bait Gel with the active ingredient Fipronil. Combat brand is a good “over the counter” choice. The ants will carry it back to the nest to feed the other 99% of the ants you don't see, including the queen, workers, soldiers and the "babies".
3. Wasp Spray aerosol cans. This stuff shoots a stream about 10 feet away and will drop them dead in the air. Use on wasp nests, yellow-jackets and bees. While not specifically labeled for them, it will kill just about any insect you don't want to get too close to (like Black Widows and scorpions). Any brand will do.
4. Flea Spray. Fleas are tough. Bathe and treat your pets first, clean your carpets and then treat the house.
5. Bug Bombs. These are not terribly effective, even the "prescription strength" ones in the industry are not that great. Still, I'd keep a few in stock.
6. Snap Traps for rats and mice. A dozen or two of each size should last many years, maybe forever. Try to find the ones with the big, yellow triggers. Much safer to set than the older metal ones, trust me, I've broken a finger setting a rat trap, they are no joke.
7. Rodent Bait. Decon will work, but the Combat brand (big, waxy blue blocks with the active ingredient Bromadiolone, an anti-coagulant) are better. It keeps longer and can be thrown into far corners of attics and crawlspaces.
8. Roach Bait Gel. Maxforce or Combat brand, active ingredient Hydramethylon.
9. Termiticide. A liquid will kill more than just termites and so is more versatile, but the commercially available baits (wood stakes impregnated with a stomach poison) are much more effective.
10. Building Repair Materials. Screening, caulking, steel wool, foam, etc.
Please, follow all warning labels on each product you use!


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