Wednesday, January 31, 2007

How do spider mites damage plants?

Spider mites can cause extensive leaf damage

spider miteSpider mites are tiny (1/32") plant-feeding mites (see drawing left) that are important pests in both home gardens and commercial agriculture. Even a minor spider mite infestation can do significant damage to plant productivity. Injury is the result of damage to the plant's protective outer layers, the epidermis and cuticle, that occurs as the mites feed. Research has shown that injury to these layers causes excessive and uncontrolled water loss and eventually injured plants dry out and die (see photo of injured leaf below).


Take a look at the photo of the two leaves. The photo was taken during an experiment to determine the effects of spider mite feeding on peppermint leaves. The leaf on the right was infested with spider mites, the leaf on the left was kept spider mite-free with a barrier of sticky material (not visible in this photo). After about 15 days the mites were removed and a variety of measurements were made to determine the health of "injured" vs. "uninjured" leaves.

spider mite damage experimentThe leaf that was fed on was dry and brittle compared to the uninjured leaf. When water loss was measured injured leaves (even dry ones) had far higher rates of water loss and this loss was uncontrollable. Healthy leaves are able to conserve water, especially at night. There were many other physiological differences that all related the leaf's ability to control water. Spider mite feeding disrupted the ability to control water loss by disrupting the leaf's protective layers.

Use the link below for additional information about the original experiments and references to the scientific literature.

Pantry or stored product pests

grain beetlesInsects that infest our stored foods

Now that the cold weather has arrived we can turn our attention indoors and think about getting rid of those pesky "weevils" and moths that are occasionally found in the kitchen and pantry.

Did you know that insects consume 10-50% of all stored grain worldwide? Most of the loss occurs in commercial storage but a significant amount also happens after consumers take food home and store it improperly. So perhaps we needn't worry so much about producing more food on the farm but should concern ourselves instead with protecting the food we already have in storage!

Here's some basic information about the most common pantry or stored product pests and what you can do about them at home.

Keep in mind the following points: (1) Dry pet food is the most commonly overlooked source of infestations. (2) Do not store items longer than about 2 months unless steps are taken to protect it against infestation (see below). (3) Do not store items in the thin plastic "supermarket" bags because insects can chew through this plastic; use heavy plastic, glass or metal containers instead. (4) Freeze products like birdseed, dry pet food, and flour, before placing them in long-term storage -- freezing can effectively eliminate many insect pests (see below). (5) Discard infested foods when it is found. Trying to salvage food that has become infested with insects is usually not practical and may only provide an ongoing source of infestation.

Weevils - The term "weevil" is often used to describe a wide variety of beetles and true weevils that infest seeds, whole grains, and flour. Some stored-product beetles require whole, unbroken kernels (see photo above) whereas others infest grain meal and flour.

Meal moths - Adult moths are about 5/8" across the wings. Their wings often have a broad, dark band across the back (Indian meal moths). Larvae, "worms", infest a wide variety of foodstuff including grains, dried fruits, seeds, crackers, nuts, powdered milk, dry pet food, and cereals. Webbing produced by larvae is commonly found covering infestations. You may also find moths in the kitchen or other rooms. Meal moth infestations are common in shelled or unshelled nuts, especially walnuts. Spilled pet food is another likely source of infestation.

Flour beetles - A pest of flour, this beetle cannot attack unbroken kernels. Also found in peas, beans, shelled nuts, dried fruits, spices, etc. One generation is completed in 2 to 3 months. You must find all infested foodstuff and dispose of it in order to control this insect.

Dermestid or carpet beetles - There are a number of small beetles that feed on animal hair, hide, and stored food. Dermestid or carpet beetles are notorious scavengers feeding on all manner of dead animal protein. Some of these beetles infest stored food as well. Their presence is often detected when the cast skins of their "fuzzy" larvae are found in kitchen draws or on shelves (see carpet beetle link below for photos).

A word of caution about using insecticides around food

Controlling stored product pests with insecticides is very difficult and usually
not recommended because of the proximity of food to the applied poisons. Most of the time stored product pests can be adequately managed with proper sanitation, traps and attention to how packages are sealed and stored. Most importantly, don't store foods longer than about 2 months unless you freeze them first.

If, however, insecticides are used indoors use only the new botanical insecticides, specifically those that are exempt from EPA registration (see the link above for products that are available to homeowners). These insecticides are very effective when used according to their label instructions, much safer for you and the environment, but are somewhat more expensive than conventional pesticides.

How to protect foods with cold treatment

Freezing kills all stages of stored-product pests like moths, beetles and weevils. After cold treatment foods can be removed from the freezer and stored at room temperature in a sealed container. Even packaged foods like flour, dry pet food, dried fruit and so forth can harbor live insects. If these products are placed in storage at room temperature insects will start to multiply resulting in an infestation. On average it takes about 2 months for these infestations to develop. This is why we suggest that you treat food products with cold if you plan to store them longer than about 2 months.

The rules for cold treatment are to keep the package small enough and the time-in-freezer long enough to ensure that the product completely freezes. For example, a five pound bag of flour might take 3-4 days at normal freezer temperature whereas a 1 pound box of raisins might take only 2 days. Freezer times will largely be a guess at first as there are no hard and fast rules. Just remember to keep the package small and time in freezer as long as possible.

Use the links below for specific information about identification, trapping, and control of these stored product pests.

Monday, January 29, 2007

Get rid of fleas now!

Fleas can be a problem for every dog and cat owner. Adult fleas feed on the blood of warm-blooded animals. While they also bite people, we are not their preferred host. Flea bites cause swelling and itching on both us and our pets. Immature, or larval, fleas look like small white worms. They don't bite but instead feed on hair, shed skin, and dried blood in the animal's bedding. See this page for photos of adult and larval fleas.

Below is an inexpensive flea control program that works very well; it can be time consuming but all the steps are important. If you skip any of the steps fleas may be a recurring problem. For methods that are easier but more expensive see flea control at 'Bugs.

Inexpensive flea control

(1) Vacuum rugs, drapes and furniture thoroughly . Pay particular attention to areas where pets sleep. Discard the dust bag outside because it contains fleas, flea larvae and eggs that may re-infest the house. Vacuuming is an important first step!

(2) Treat rugs, drapes and furniture, and any outdoor sleeping areas like a dog house, with methoprene (IGR; see below). Use these products according to label instructions. Some methoprene products also contain other insecticides like pyrethrum.

Insect growth regulators (IGR) act by disrupting normal flea development -- non-biting larvae never develop into adults and eventually die. IGRs are virtually non-toxic to humans and pets and are long-lasting, up to 7 months by some reports. The downside of IGRs is that they are slow acting.

(3) Shampoo your pet with a good quality flea shampoo at the same time as steps 1 and 2. Repeat the shampoo in a few weeks when you notice adult fleas again.

Use of flea collars

Flea collars do pretty well at keeping ticks off the front half of dogs; however, they don't have much value against fleas -- especially if the home is infested.

Outdoor treatments

According to the best information we have, outdoor insecticide treatments are not needed and of little value. This is because fleas live in the animal's nest or bedding. They don't survive for long away from their animal host. So, you can skip the general lawn treatments for fleas.

Use of foggers or "bombs" (total release aerosols)

Aerosol foggers or "bombs" are popular with some homeowners. The idea is that the aerosol insecticide somehow penetrates into cracks and crevices that you couldn't reach by other means. In fact, total release aerosols do a poor job of coverage because they essentially throw insecticide into the air thereby treating only exposed surfaces as it lands. On the other hand, liquid formulations, carefully applied with some type of pressure applicator, will achieve much better coverage and might even be less expensive.

See the flea control articles below for more detailed information.

Sunday, January 28, 2007

Black fly "mystery" at Scotty's Castle solved! :)

The mysterious appearance of black flies, which are normally found around white water rivers and mountain streams, at Scotty's Castle in Death Valley National Park, one of the driest places on earth . How do these aquatic insects survive in this desert??? The mystery is explained at the Black Fly @ Scotty's Castle page.

Saturday, January 27, 2007

Borate (boric acid) compounds for insect control

We frequently get questions about the various borate products on the market to control insects around the home. These products are used to control ants, cockroaches and structural pests like carpenter ants, powderpost beetles and dry-rot fungi.

General characteristics

Borates offer a low toxicity alternative to conventional insecticides, but
are slow acting and may take several weeks to be completely effective. Borates are also generally long lasting, if kept dry. And, borates are generally not used outdoors because of they are soluble in water. Borate is primarily an insect stomach poison and fungicide. Stomach poisons must be eaten by the pest to be effective.

Borate Products

Timbor and Bora Care (and a few others) are products for structural pest control (termites, carpenter ants and wood-boring beetles). Timbor is a powder of 98% disodium octaborate tetrahydrate, a sodium salt of boric acid, and Bora Care is a 40% solution of the same compound plus ethylene glycol.

Timbor can be used to treat wall voids for carpenter ants and/or cockroaches, silverfish, etc. Timbor powder may also be dissolved in water and applied as a solution. Bora Care, on the other hand, is always applied as a spray to protect wood against chewing insect attack (carpenter ants, termites, wood boring beetles, etc.) and dry-rot fungi. Bora Care contains ethylene glycol which may help in penetration of wood fibers.

Borate powder ("Roach Pruf", "Roach Powder") is an excellent alternative to conventional insecticides for cockroach control as well. The powders can also be formulated as a homemade ant bait. My own experience is that borate powders, when used correctly, are very effective but slow acting. When used to dust wall voids, it will eliminate carpenter ant colonies and prevent re-infestation. Sometimes borate treatments are combined with a faster knockdown insecticide like pyrethrum.

Thursday, January 25, 2007

Clothes moths added to 'Bugs

I've just posted a new page about clothes moths at our 'Bugs site. Clothes moth larvae ("worms") can do significant damage to many kinds of natural fabrics. This new page explains identification, trapping and control of clothes moth.

Saturday, January 20, 2007

Happy New Year! to the friends of 'Bugs

2006 was a good year for 'Bugs overall. At the start of the year, however, 'Bugs was still in the clutches of the dreaded Google "sandbox" and, as such, our visitor count was fairly low. We got out of the sandbox, briefly, in March but it was not until the end of June when we finally emerged for good (I hope!).

During the year we added 48 new pages with topics from ant bait to insect stings.

New pages already in '07

Pest Control Suppliers Online
Flea Traps
Ant Control
Synthetic vs. Organic Pesticides

We are looking forward to seeing all of you in '07! Let us know if we've missed an important Bug topic.