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The Pest Monitor

Volume 8, No. 3

August 2000

A well-informed employee is the best salesperson a
company can have. Edwin J. Thomas

 

Quiz Answered

The question from the last newsletter was "list and give a brief description of four different treatment techniques which can be used within a structure" A number of things could be listed and your list may not be the same as mine; however, the thought process is what counts.

 

Identification. If there is any doubt about the pest, this should be the first thing that is done. Too often the phrase "sweet ants" or "&&#* ants" is used when referring to an ant problem. Not only are the terms not very descriptive, but not very professional (more about ants later). Bottom line--if one does not know what the pest is, how can one develop an appropriate control program around this pest?

 

Baits. This is a very good pest control method for some pests. Baiting can be done in a fairly short period of time, and the insecticide is confined to a specific spot within the structure. Baits may come as gels, liquids or solids. The solid and gel materials are probably more widely available and may be easier to handle than the liquids.

Sprays/Dusts. Do all pests come to baits? Of course not. Spiders are the first example that comes to mind. If you are dealing with such a pest, then the sprayer/duster is still an acceptable method of pest control. Placement of the spray or dust into harborage sites used by the pest is the better treatment technique; however, there is probably more baseboard spraying done than the industry would like to admit. Still, the use of sprays or dusts is an effective way to eliminate pests.

 

Aerosol Applications. This formulation is useful in the control of exposed insects and may be used in homes or in large warehouses. Aerosols/fogs are formulations that have particle sizes that range from 0.1 to 50 F (100 F equals 0.004 inch). This formulation is not a fumigant. It is not in the form of a gas. An aerosol may be applied by placing a concentrate into an applicator or applied from a pre-packaged system. Placement of the aerosol into a harborage site, depending on the pest situation, is the best policy. If the product is directed into the harborage, more than just exposed pests are controlled.

Ant Identification

Why is it that most owners and technicians do reasonably well identifying insects such as cockroaches and termites, but do not do so well on ants? One of the reasons is probably size. The smaller the insect, the harder it is to see the critical characteristics needed for identification. Size, however, can be overcome. It will require a good quality hand lens or a small microscope. Viewing a specimen under a scope gives a more stable platform, especially when viewing some of the smaller details. Finally, one should be familiar with some of the basic morphological characteristics of ants.

There are thousands of ant species in the world. But the question is, how many of these will you encounter in a year? Marion Smith in "House Infesting Ants of the Eastern United States" (USDA, Technical Bulletin No. 1326, 1965) lists 49 potential house infesting ants. Hedges (PCT, Structure-Infesting Ants) narrows this down a bit further by listing only 20 species that are potential pest ants. Based on the ants which I receive for identification, the number can be reduced to six species. These are carpenter ants (two to three species), odorous house ant, Argentine ant, acrobat ants, fire ants, and the pharaohs ant. I have seen one sample of the little black ant. My data is probably not a true representation of the pest ants one might encounter, but if these six are used as a basic starting point, then others can be added as needed. The six ants which I have listed will be used as examples in the following discussion.

 

Basic Ant Morphology (Fig.1): A number of body characteristics can be used in the identification of a particular ant. The areas that this discussion will concentrate on are the pedicel, antenna, and the thorax.

  • Pedicel. This is the narrow stalk between the thorax and the gaster. The pedicel is actually the first part of the abdomen, and the combination of the pedicel and the gaster is the abdomen. The pedicel contains either one or two nodes.

     

Fig. 1.  Fire ant showing the two nodes on the pedicel and the irregular nature of the thorax top line.

  • Antenna. The first antennal segment for the head is called the scape and, in some cases, the segment will extend above the top of the head (crazy ant is a prime example). Total antennal segments and the presence or absence of a club an the end are also important points.
  • Thorax. There are two features on the thorax which can used to identify ants. These are the top line of the thorax and whether or not the back of the thorax is "armed" or not "armed." Armed is defined as the presence or absence of spines. The spines may be on the very back of the thorax as in Fig. 2 or, in some ant species, they may be located forward of this position.

Lets take these characters and apply them to the ants, previously mentioned:

 

Number of Nodes. The number of nodes on the pedicel can be used to place ants in groups. For example, if the 20 species listed by Hedges are divided by the number of nodes, one will be looking at 10 species of ants with one node and 10 species ants of two nodes. The same division holds for the six species that I list. Three are two node and three are one node ants. The two node species are acrobat (several species), fire, and pharaohs ants, and the one node species are carpenter (several species), Argentine and odorous house ant.

 

Two Node Species

 

Acrobat Ants (Fig. 2). The two nodes on this ant are not as distinct as they are on other two node ants; however, the presence of spines on the back of the thorax , the connecting point of the pedicel to the gaster, and a heart shaped gaster are good characteristics to use in the identification of this ant. The pavement ant also has a pair of spines on the thorax but the nodes are much more distinct and the head and some areas on the thorax are grooved.

Fig. 2.  Acrobat ant showing the "armed" nature of the thorax.

Fire Ants (Fig. 1). There are two species of imported fire ants in Mississippi. These are the red imported fire ant Solenopsis invicta and the black imported fire ant, S. richteri. The red occurs in most of the state, with the exception of the northeast corner, and this is where the black is found. There is an indistinct band between these two species which contains a hybrid ant. The hybrid will not be covered in this newsletter.

Both the black and the red have two very distinct nodes, and the antenna has ten segments, with a two segmented club. Most ants you will encounter will have 12 segments. If the ants are field collected, the mound will be a very good indicator as to whether or not you have fire ants. Both species build the typical dome shaped mound. Both species have a well developed stinger (Fig. 1).

Pharaohs Ant (Fig. 3). This ant has two very distinct nodes, and the antenna has a three segmented club. The body color ranges from yellow or light brown to reddish. The thief ant has two nodes and is similar in color but has ten antennal segments, with a two segmented club. Pharaohs ants do not appear to nest outside. Most reports seem to indicate that this ant is "exclusively" an inside nesting ant.

Fig. 3.  Pharaohs ant showing the three segmented club and the two nodes on the pedicel.

One Node Ants

 

Carpenter Ants (Fig. 4). There are several species of this ant in the state and most people are probably familiar with the large black carpenter ant, Camponotus pennsylvanicus. All carpenter ants have one node, and the top line of the thorax is very even. Compare the area in Fig. 4 marked "even top line" with the same area in Fig. 3. Notice the uninterrupted nature of this line in the carpenter ant vs. the pharaohs ant. Carpenter ant color will vary with the species. It will vary from solid black to a reddish color or mixtures of red and black. The one in Fig. 4 is Camponotus castaneus and is yellowish to yellowish red. So colors within the carpenter ant group can vary.

Fig. 4.  Carpenter ant showing the even top line of the thorax.   Notice the one node.

Argentine Ant (Fig. 5). It seems that this ant is becoming more abundant. The antenna has 12 segments and the scape does not extend above the top of the head. It has one node with brown to light brown body color.

Fig. 5.  Argentine ant showing the node and scape.  

Odorous House Ant (Fig. 6), OHA. It is very easy to confuse the odorous house ant with the Argentine ant (AA). The major difference is the node. The odorous house ant has one node, but it is not very obvious when the ant is viewed from above or the side. Compare this area on the OHA with that of the AA. The OHA may also be darker in color; however, if you do not have the ants to compare side by side, this may be a hard character to use.

Fig. 6.  Odorous house ant showing the reduced nature of the node.

These are some of the differences which can be found in the six ants that are commonly sent to the Entomology Lab. for identification. Yes, I know it is much easier when the pictures are enlarged; however, as mentioned, this can be overcome with a good quality hand lens or a small microscope. The industry is always looking for some new magic gizmo or formulation and something as old as the microscope is overlooked. It will help.

The next question is "why is it important to identify the ant in question?" The first two things that come to mind are professionalism and treatment. I think it is much better to tell the client that "x" ant is a carpenter ant or a pharaohs ant, and this is how this particular ant develops. The alternative is to tell them that it's just a sweet ant, and this "stuff" will get them. In your opinion which sounds the best?

TREATMENTS! Some ants will come to baits and some will not. The pharaohs ant baits much easier than some of the other species, while the Argentine ant is the hardest to bait (in my opinion). The other ants will probably fall somewhere between these two in their bait acceptance. More about Argentine treatments in the next issue.

Rules and Regulations

A new rules and regulations tape has been produced and is now available at $15.00 per tape. This tape will replace the one which has been used in the registered technician program. It is available from my office, and the address will be at the end of the newsletter.

Formosan Bits and Pieces

  • This termite has been found in one structure in Flora, MS (Madison, Co.). The structure has been treated but I do not know who treated it or how it was treated. If you work in this area, it might be good to keep your eyes open next spring.
  • There are still some who think that the Formosan is not a subterranean termite. IT IS A SUBTERRANEAN TERMITE. It is in the same family as the native termites, Rhinotermitidae.
  • It seems that there is some discussion about the occurrence of this termite in Memphis. In one case, the termite was identified from a golf course, but it turned out to be a native species. Supposedly, three swarmers were found next at a house, but when walls were removed, no termites were found. It seems odd that only three swarmers were present. It generally takes five to eight years for a founding colony to reach the point that it is ready to swarm. When this point is reached, thousands of males and females will emerge. The color of the Formosan is the same as the "light southeastern subterranean termite" Reticulitermes hageni. Do not confuse the two. Hageni will swarm from mid- August to September, while the FST swarms in May and June.

Quiz

You get a call about small flies occurring in a home. What insect or insects might be involved in an infestation of this type and what approach will you use in dealing with a complaint of this nature?

 

 

James H. Jarratt, Ph.D.
Box 9775
Mississippi State, MS, 39762
jjarratt@entomology.msstate.edu


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