Quiz Answers: Pantry Pests

Here are the answers to yesterday's quiz on pantry pests. As the weather gets colder, there are fewer outdoor bugs and our attention is turned to household invaders. But pantry pests can and do infest during all seasons. 

1. The best way to find the source of a grain moth infestation is (d) inspect all dry goods. Pheromone traps will catch adult moths and may help you target a particular area, but the best way to find infested product is to look in every bag, box and package - whether opened or not. If you find frass, the silky webbing pantry moths leave behind, discard the dry goods in which the frass is found. Usually one box or bag will contain the primary source, and you will know it when you find it. But secondary sources may be present. Don't stop until all dry goods are inspected. And check also for webbing on the under side of stored canned goods!

2. Cigarette beetles are most commonly found in (c) dog food and paprika. When checking for the source of pantry pests, don't forget the spices and dry pet food. If you have decorative items like wreaths that are made out of natural products, check these too.

3. Pantry moths develop from egg to adult in (b) around 10-14 days, depending on temperature. If you have removed all the adult moths and their larvae, but find more in 10-14 days, there was a source you missed. Check dry goods again, and clean the shelves with a disinfectant cleaner to kill any remaining eggs.

4. Meal worms usually spend the winter (b) as larvae. It is difficult if not impossible to determine what the adult bug will be just by inspecting larvae. And larvae are not commonly susceptible to pesticide sprays. But boric acid will stop them in their tracks. If you find any kind of larvae, clean the area with a good disinfectant cleaner and look for the source. These pests love to hang out in bird feeders too.

5. It is rarely effective to use insecticides against pantry moths because (a) larvae and pupae are not controlled with insecticides. As noted above, larvae crawl right through liquid chemicals. And if the larvae are not controlled, the problem will persist.

6. (B) Larval Indian meal moths leave webbing, or frass. They spin the web as they become fully grown and leave behind silken threads wherever they crawl. This is the frass mentioned above - and is easily noticed as it caused clumping in rice, oatmeal or cornmeal and is sometimes apparent on the outside of a box or bag of infested product. Since the frass usually contains excrement, it should be disposed of immediately.

7. Small, wormlike bugs in the pantry are usually (c) larval moths. But as mentioned, larvae are difficult to identify. Any larvae found should be taken seriously as a pantry infestation. They can (and will!) chew holes through cardboard or plastic packaging materials to get to the food inside. One method of killing pantry pests before they hatch is to store dry goods in the freezer for a couple of weeks. Since the product may be infested when you bring it home from the store, storing it in heavy plastic or glass containers may not be sufficient.

We hope you've learned something useful about common pantry pests. As with all pests, if you cannot solve the problem yourself, contact a pest professional. But in the case of pantry pests, what you can do yourself is really the best solution to the problem.

Tuesday's Quiz: Pantry Pests

Today's quiz asks you to test your knowledge of common pantry pests. These are stored product pests that infest dry goods in your pantry - including moths and weevils. See how much you know about these uninvited guests.

1. Grain moths often come in pre-packaged food from the store. What is the best way to find the source of infestation?

a. Put out traps.

b. Look in whole grain foods like rice and oatmeal.

c. Call a pest professional to check your cabinets.

d. Inspect all dry goods.

2. Cigarette beetles are a common stored product pest (see illustration above). In which stored products are they most commonly found?

a. sugar and flour

b. cornmeal and oatmeal

c. dog food and paprika

d. rice and coffee

3. Pantry moths develop from egg to adult in about

a. 3-5 days

b. 10-14 days

c. 16-20 days

d. 3-4 weeks

4. How do meal worms usually spend the winter?

a. in hibernation

b. as larvae

c. as pupae

d. under ground

5. It is rarely effective to use insecticides against pantry moths because

a. the larvae and pupae are not controlled with insecticide

b. the moths actually feed on insecticides

c. insecticides have little or no residual effect

d. moths can fly away from the poison

6. Indian meal moths are one of the most common of stored product pests. The "webbing" or silk mat that identifies their feeding area is left by

a. the adult moths

b. the larvae

c. the pupae

d. all of the above

7. Small, wormlike bugs in the pantry are usually

a. parasites that feed on moths

b. undeveloped beetles

c. larval moths

d. worker moths

Answers to today's quiz will be published in tomorrow's blog.

Hallowe'en Bug News

We saved the scariest and most disturbing bug news to share today, in honor of all the little vampires and ghouls out there. This strange but true news comes from Discover Magazine's blog, in an article here. Apparently, scientists have discovered a new tendency in bugs: they crave blood! For mosquitos and bed bugs, this is not unusual. But these are insects that generally have been attracted by sweet substances, and are now looking for salt.

According to the article, research teams studying insects in Peru became puzzled when they were attacked by swarms of tiny bees. The bees were trying to get a taste of their sweat! Animals, and apparently even insects, need salt to maintain water balance in their cells.

Armed with new evidence and theories to test, the scientists baited ants on the Peruvian forest floor with vials of both sugary and salty water, then counted the ant species they baited. Ants living close to the ocean, and thereby near a source of salt, preferred the sugar. Inland ants preferred salt. Further, the scientists found the salt cravings were only seen in vegetarian ants, as carnivorous ants got enough salt from the bodies of their prey. Their report was published in the Proceedings of the National Academy of Sciences.

Which brings us to vampire moths. In another study, entomologists researched a population of fruit-feeding moths (Calyptra thalictri) which evolved the habit of feeding on blood. These moths, native to Russia, use their long, sharp  tongues to pierce human skin now instead of peaches and pears. They have been observed sucking blood from the scientists' hands for more than 20  minutes at a time. According to the Discover article, only male  moths engage in blood-feeding. The scientists suspect they are offering the salt from the blood as a gift to females during copulation. Happy Hallowe'en!

Moth Wars

In the classic Japanese horror flicks featuring Mothra, giant moths cause great destruction. To the right, you see Mothra in her larval form destroying the Tokyo Tower (Mothra, 1961). The film makers got it right in this shot. It is the larval state of pantry moths that causes all the damage. 

We have posted information about grain moths here before, but since they were recently featured in an online article - and because they are a year-round problem here in San Diego, we have decided to revisit the topic with additional information and tips on how to get rid of these troublesome pests.

The article posted on recordonline.com discusses the Indian meal moth. A similar pantry pest is the angoumois grain moth. Both these insects infest grain products, their larvae feeding on flour, rice, cornmeal, oatmeal, dried fruits, nuts, bird food and dried pet food, among other pantry items. If you have seen adult moths flying in the kitchen or pantry areas, control can be achieved with careful examination of stored foods - any dry goods you have in the pantry or cabinet areas. Check also bird seed, dry dog food, even fish food and stored spices. When moth larvae feed, they spin webs, leaving behind silken threads where they have travelled. Small particles of food often adhere loosely to the thread, causing the food to clump. Often the webbing left behind is obvious on the packaging. If this webbing is visible, throw out the entire package. The larvae can bore holes through cardboard and plastic packaging materials, so even foods that have not been opened should be examined. Any infested food and packaging should be disposed of in outdoor trash receptacles. If possible, store uninfected foods in airtight glass jars or in the refrigerator or freezer.

As you empty pantry shelves to examine food, remove all food container - even canned goods - and check for evidence of larvae on the bottoms of cans, inside drinking straws, and between stored  paper or plastic bags. Remove shelf paper. Clean shelves first with a vacuum cleaner and then with soap and water, or a disinfectant cleaner. Be sure you clean even cracks and corners, as small amounts of flour or meal may have accumulated there as well. A thorough scrubbing of the pantry area, and inspection of all dry goods will usually be sufficient to eradicate the problem. Pesticides are usually not necessary. If adult moths persist, a pheromone sticky trap can help relieve the problem before they lay more eggs. Getting to the source of the infestation is a major part of moth control. If left untreated, this pantry problem can become nearly as big and scary as the moths in the movies. Don't let this happen to you!

Mystery Bug Week, Part V: Of Words and Worms

Fly larva
Moth larva

The mystery in this last Mystery Bug Week post is two-fold. The first mystery is more etymology than entomology. We find our customers would rather say they have "bugs" than "roaches," rather have "mice" than "rats," and rather have "worms" than "maggots." No one wants maggots. We can't blame them! In fact, what most people report as "worms" are some kind of larvae. Doesn't that sound better? 

The second mystery is how to tell what kind of larvae they are. In the larval state, most common flying bugs look remarkably similar. There are variations in size, of course, but it is nearly impossible to tell fly larvae (maggots) from moth larvae (see photos above). One simple way to solve the mystery is to take notice of any increase in populations of the adult bug. Have you seen flies or moths buzzing around the house or in the yard? Identifying the adults those worms will turn into is critical in controlling the problem. We have discussed pantry moths in a previous post. They are a stored product pest, so if you consistently see moths in the house the chances are good they are coming from the kitchen or pantry. Find the source, eliminate it, and the problem is solved. House flies are less localized. They could be coming from anywhere - so a bit of detective work is needed to solve the mystery of where they are breeding. Flies need moisture, and usually breed in some kind of decaying matter. Check grass clippings and mulch piles outdoors. Inside, check house plants to see that they are drying out between waterings. Indoors and out, follow your nose. If there is a dead rodent in the wall void or a potato behind the fridge, these would be great sources for breeding flies. Whatever you choose to call the larvae that invade  your home, they are a problem that can be solved with a bit of detective work.

Butterflies are Free...

... but moths can cost you! Common pantry pests in San Diego County include Indianmeal moths and the Angoumois Grain moth, stored product pests that can invade dry goods in the kitchen. You may bring them home in a bag of rice or a box of oatmeal from the store. Once in the door they cause all kinds of trouble. We are often asked if the moths in our customers' pantries will also invade closets and damage clothing. The answer is no. Although similar in appearance, clothes moths have different eating and living habits. Grain moths are much more visible -  you will see the adult moths in greater numbers, and usually in the kitchen area. But getting rid of them can be time consuming and frustrating. In order to avoid pantry moths, freeze all grain-based products you buy for 4 days before storing them in airtight containers. This is especially important if you buy grain products from bulk bins. Be aware that moth larvae can bore through plastic bags and cardboard boxes. 

If you already have an infestation, go through all grain based stored products. This includes bird seed and dog food, spices, nuts, raisins, cereals, pastas, even chocolate - look through everything! If you find webbing, clumping or larvae in a box or bag, throw it out. Clear off pantry shelves and clean with a good disinfectant cleaner or vinegar solution. This process should eliminate most infestations. Occasionally moth larvae still hatch out from eggs left in the cracks and crevices of pantry shelves. If all your grain-based products are in air tight containers, you can safely put out a moth trap , available at some local retail outlets or online here, to catch ambient adults as they hatch.