MSU logo

The Pest Monitor

Volume 9, No. 1

February 2001

I Can Live for Two Months on a Good Compliment. Mark Twain

 

When was the last t time you Complimented one of your technicians on a Job well done ?

Quiz Answered

The quiz will be a continuation of the fly discussion from the last issue. In that issue, the families Drosphilidae (fruit flies) and Psychodidae (moth flies) were discussed. In the closing lines of that discussion, I stated that three other families would be included in this issue and a discussion of these families follows.

Small flies are often referred to as a gnat; however; at least two groups of flies, Mycetophillidae and Sciaridae, incorporate the word gnat into the general name for the family. These names are "fungus gnats" (Mycetophillidae) and "dark-winged fungus gnats" (Sciaridae).

Fig. 1.  Fungus gnat in family Mycetphillidae.

Both groups can occur in homes or office buildings, and they are usually associated with areas that have potted plants, planters, or maybe aquariums, terrariums, atriums or similar structures within the building. Mycetophillids are small flies ranging in size from four or five millimeters to as much as 13 millimeters long. The legs on these insects are very long, and they can be seen running over the soil surface in areas listed above. Coloration is dark, and they may be difficult to see at first glance. The antenna is quite variable in this group of insects, so do not let the long slender antenna in figure one throw you off. The antenna in figure two is given as a comparison. The antenna in this species is shorter and thicker; however, figure one and two are found on insects in the same family.

Fig. 2.  Another antennal type found in the family Mycetophillidae.

Insects in the family Sciaridae are very similar to those found in the mycetophillids in size and shape; however, the eyes will meet to form an "eye bridge" across the top of the head.

Fig. 3.  Dark-winged fungus gnat in the family Sciaridae.

The last group is the family Phoridae or humped backed flies. This group is quite varied, and the species range from those that occur in decaying animal or vegetable matter to those that are parasitic in ant or termite nests. In fact, the family has been in the news recently as some species are being studied as possible biological control agents for fire ants. The ones most often encountered in structures are those that are associated with decaying material.

Phorids are small flies three to four millimeters long that are usually tan to dark brown in color, and they do not have the red eyes found in the fruit flies. They have an arched back that gives them a humped appearance, hence the name hump backed flies. The head is also fairly small in comparison to the rest of the body.

Fig. 4.  Phorid or hump-backed fly.

Phorids can be found in a variety of situations within a building, and these are usually associated with some decaying material. Examples are garbage disposal units, dirty mops, food scrapes under the edges of baseboards, flower vases, broken discharge pipes under foundations, improperly operating evaporation pans under freezers or refrigerators, clogged condensation discharge systems associated with air-conditioners, planters, atriums, etc.

 

Management Guidelines. These are the same as were discussed for fruit flies and moth flies. Adults can be controlled with a space spray, but it will not be long before you will have to go back as adults will continue to emerge from the source. So finding and eliminating the source will be the control method of choice. In summary :

  • Fruit Flies B Associated with decaying material such as fruits or vegetables. The decay is caused by yeast which will produce a vinegary or wine smell.
  • Fungus Gnats B Insects of this type may be found within one of two families, Mycetophillidae or Sciaridae. They are usually associated with the over watering of potted plants, and also may be found in atriums, inside water gardens and similar situations.
  • Phorids B Found in association with decaying animal or vegetable material. Might even occur in the same situations as the fungus gnats.
  • Control option of choice is to find the breeding site and eliminate it from the structure.

     

 

More on Termite Pre-Treats

After the section on pre-treats in the last issue, I stated that if anyone had any suggestions or comments I would be glad to include them is this issue. The only comment which I got was that other factors are involved in pre-treat pricing other than chemical, overhead and profit charges. As I understood this persons comment, the reason for charging a very low pre-treat price was to pickup renewals from the purchasers of the property. I have never made a dime on a business sell so my reasoning may be flawed but this sounds like the old adage of robbing Paul to pay Peter, and this does not work in the long run. Would this same concept work in other business? Let=s suppose that IBM has a computer that cost them $1500.00, but they sell it for $500.00 and hope to recoup the $1000.00 on a service contract over the course of 10 years. I do not see this happening. A paraphrase of another old adage says that a "profit in hand is worth two profits at some point in time." Enough on pre-treats.

Termites are Aswarming

Evidently some termite colonies hit a period of swarming back in early January and the question is are you ready for the termite swarm season? Consider the following points:

  • If you did not use your equipment over the winter, is there any possibility that it has rupture lines due to the cold weather we had in November and December?
  • Were any hoses or connections leaking at the end of last year? If so, repair these, especially if you will be taking the hose into buildings.
  • Do you anticipate changing chemicals for the coming year? If so, review the label of the product you intend to use so you will be ready.
  • If you work in the southern third of the state, do you know the difference between the Formosan subterranean termite and the native species of subterranean termites?
  • Can you identify the swarmer if it has lost its wings? Sometimes we get tunnel vision and if what we are confronted with is a little different, we hesitate because it doesn't=t fit what we are used to seeing.
  • Can you tell the difference between termite damage and the damage caused by other wood destroying insects?
  • Do you give bids over the phone before ever seeing the job site?
  • Brush up on foundation types and be prepared to change your treatment techniques to fit the foundation type.

Moles and Voles

Occasionally you may be asked questions on moles and voles. Even if you do not do pest control in the lawn, the following will at least help answer these questions.

 

Moles. The mole which occurs in the southeast is the eastern mole, Scalopus aquaticus. The male is slightly larger than the female in all species. Males average seven inches in length and weigh about four ounces, while the females are about 6.5 inches long and weigh approximately three ounces.

These animals are insectivores and even though their diet is mainly insects, they will eat other arthropods. The stomach contents of 100 eastern moles showed this variety. The following numbers are the "number per stomach:" white grubs 64; earthworms 49; beetles 67; centipedes 25; spiders 23; ants 19; seed pods or husks 43, etc. It is interesting to note that although these animals are insectivores, they do eat some plant material.

Moles are thought to be loners, and most research in the plains area show a population density of three to five per acre. This number may be higher in the southeast due to more frost free days which allows more insect generations per year. If there is more food, then the carry capacity of an acre may be higher. As moles are hunting for food, mostly done at night , they will leave the characteristic mounded runways in the lawn. "Swimming" through soil uses large amounts of energy, hence the mole will eat 70 to 100 percent of their weight each day. In order to find this amount of food, a large home range is needed by each animal.

The den area may be under a portion of a tree or under a sidewalk, and these areas tend to be dryer than the surrounding area. The gestation period is approximately 42 days, and three to five young are born, mainly in March and April. I could not find any data on the number of matings that may occur over a year. I would guess no more than three, and it may be only one.

Fig. 5.  Mole. Note that the feet are modified for digging.

 

Voles. These animals are often called meadow mice or field mice, and they are found in the genus Microtus. They are small compact rodents with stocky bodies, short legs, and short tails. There are 23 species in the United States and the one found in our area is the pine vole, Microtus ochrogaster. This vole is four to six inches in length with soft dense brown fur. The underside color is gray mixed with some yellow or cinnamon.

Pine voles are basically a plant feeder, and their diet contains tubers, bulbs, grasses and bark. Bark is usually eaten in the fall and winter. Occasional foods might include snails, insects and animal remains.

Fig. 6. Vole.  The animal has a mouse appearance and it is a rodent.

Most reproduction takes place in spring and summer, with one to five litters being produced during this time. Litter size averages three to six, with a gestation period of 21 days. The young are weaned in about 21, days and females mature in 35 to 40 days. Populations will vary from year to year and extremely high populations can occur. In some areas, 200 to 500 voles per acre can occur. In most situations, two to six would be average.

A few vole species will build surface runways; however, the pine vole has a system of underground tunnels that it uses as it moves from area to area. Pine vole tunnel systems will often be located along ditch banks, rights-of-way, or other unmanaged areas. The stacking of mulch, eight to 10 inches high, around the base of shrubs or young trees provides an excellent harborage area for voles. This "invites" bark gnawing by voles, especially during the fall and winter.

 

Controls. There are a number of, what I refer to as "folklore," controls around for moles, and there is no data to support these methods. The one that you hear about the most is that if one puts juicy fruit gum into the tunnels, the moles will feed on the gum which gives them a terminal case of constipation. Consider the food source of moles---insects, centipedes, spiders, etc., and the first question that comes to mind is "why would the feed on the gum?" The gum story is right up there with putting out corn meal or grits for fire ant control. The only control method that will control moles is trapping which is time consuming. The mole has to be using the tunnel on which the trap is set, and it may take several days for them to revisit an area. Considering the low population numbers per acre, two or three catches is all one would need to clear up a particular yard. Some fumigants are registered for mole control; however, fumigants could possibly kill roots of nearby plants and grasses.

There is a zinc phosphide bait (Restricted Use) available for vole control; however, I would be reluctant to use this material around a home. Be that as it may, it is registered in Mississippi. The other method is to trap, using snap traps baited with apple, potato or some of the plant material on which they are feeding. This may not work, particularly if the voles are feeding on bulbs or tubers below ground.

Pesticide Issues

If a reason cannot be found for why some anomaly is occurring in nature, the initial impulse is to blame it on pesticides. The latest is on the declining frog populations which I thought had been decided (a trematode infection); however, the U.S. Geological Survey released a report this past December again blaming pesticides. Researchers for this organization speculated that drift from the application of organophosphate pesticides made in the eastern U.S. may be responsible for amphibian deaths in Sierra Nevada lakes. This is quite different from a story printed in the N.Y. Times (November 29th) reporting on a U.S. Fish and Wildlife study that targeted the stocking of fish-less waters in the Sierra Nevada waters with trout. It seems that these trout like to feed on the amphibians, and they were drastically reducing the amphibian populations in these lakes. The agency urged all states to reduce trout stocking or even to remove stocked trout from some fishing spots.

The rush to judgment can also be found in the popular media concerning genetically modified foods. The overall perception from these sources might lead one to believe that everyone is deathly afraid of this technology. Opposite results were found in a survey conducted (conducted for the Grocery Manufacturers of America) by KRC Research in October 2000. The results demonstrated that over three-quarters of the respondents were aware of genetically modified crops, and over half were aware of genetically-modified food recalls; however, the public remained positive about the benefits of agricultural biotechnology. Two-thirds of the respondents said that they would buy produce that had been genetically modified to require fewer pesticides or if the foods were modified to contain more vitamins or nutrients.

Neither of these reports affect your use of pesticides or technology; however, it does show that there are very divergent views on why things happen. Continue to use the insecticides available to you in a safe and efficient way.

Quiz

What is the main active ingredient in products such as Drione, Dri-Die, and Tri-Die and how would you use these products in pest control program?

 

James H. Jarratt
Entomologist
Mississippi State University
Extension Service
Box 9775
Mississippi State, MS 39762
662-325-2085
jjarratt@entomology.msstate.edu


A black line that separates the body text from footer information