Friday, July 20, 2012

Fire Ant Mystery in Harris County, Texas

While checking my email Monday I received this report from Sean McGuire in Harris, County, Texas:

“I ride my bike on a concrete bike trail between Pasadena and La Porte along Fairmont Parkway.  I've notice several times, especially during wet weather, that fire ants will form long trails down the trail.  Not too unusual, except that they seem to exactly follow the tire tracks of bicycles - picture the muddy track that a bicycle would make if it had gone off in the mud then tracked the mud down the trail including where the front and back tire separate in a turn.  Except that is not the case - the concrete is clean, just long trails of fire ants.  I can only think that the bicycle tire leaves behind some unseen trail or scent that the fire ants follow.  The other unusual thing is the mass quantity of ants and how far they follow the tire track - at least 1/4 miles or more.  Again they perfectly follow the apparent unseen track of a bicycle. 

I've attached a picture.  Just curious if you have seen anything like this or could explain this behavior.

Sean McGuire”

Photo of fire ant foraging trail on bike path

Additional view of fire ant foraging on bike path

Closer view of fire ant foraging trail on bike path
Wow, what an interesting observation.  Thanks Sean for recognizing this as an unusual phenomena and documenting it for us.  It does appear that the ants were attracted to the path of the bike tires for some reason.  

 This email was passed along to several researchers who are an authority on fire ant behavior. 

Dr. Bradley Vinson, Professor, Department of Entomology, Texas A&M University, College Station, TX replied:

“It does look like the ants are following a trail. What is interesting to me is that they are following the edge of the bike tires rather than the center. It would appear that they are following an odor or contact chemical trail. It would be interesting to pull a bike tire across a pavement and see if ants follow it. But tires from different companies might or might not have the same chemicals. Also the tire that led to the trailing could have gone through something that contaminated the tire and this would likely lead to 2 parallel trails (something on the side of the tire). It appears to be really attractive; a lot of fire ants are out on the trail.”

Dr. Bob Vander Meer, Research Leader, Imported Fire Ant and Household Insects Research Unit, USDA, Agricultural Research Service, Gainesville, FL, replied:

“That is an impressive photo!!! A while ago there was interest in fire ants being attracted to rubber bands used to hold newspapers together. Consistent results were hard to get so the mini-project was abandoned. A similar episode occurred when it was observed that fire ant workers followed a trail made with a ballpoint pen. So, it is possible that compounds in bicycle tires are influencing fire ant behavior. Maybe a colony was caught in migration mode and became trapped by the irresistible smell of tire residues on pavement! The number of ants suggests colony migration.”

Foraging fire ants respond to various odors.  In fact they use odors (pheromones) for all kinds of communications.  A simple explanation of this communication activity can be found here: 

and here: 

Fire ants use their stingers to periodically mark the ground and leave a chemical pheromone trail:
  •     To mark trails to food
  •     To mark trails home
  •     To recognize their queen
  •     To recognize other worker ants from their colony
  •     To alert the other ants of danger or intruders
  It would appear from this photo that some foraging ants were attracted to an odor that was on the tires of the bicycle.  Who knows what is was, but they were attracted to it.  Once they started following the trail they laid down a pheromone trail for other ants to follow.  The original attractant may be long gone, but the pheromone trail remains, and intensified as others ants pass.  With the rains we have had recently in the Houston area, the fire ants could be migrating to a higher area and the cement bike trail is a perfect highway to do this on.

Informational video on fire ants moving a colony from eXtension site: 

Monday, July 16, 2012

American Cockroach vs your home!

I was sitting watching TV the other night and what did I see but an aircraft carrier cruising across my floor!  No, wait; it is just one of those large cockroaches.  Have you had a similar experience?
 With the recent rains in the Houston area, many insects’ habitats have been disturbed and you may see some around your home as they try to get out of the wet conditions.  One you will commonly see is the American cockroach (Periplaneta Americana).

American cockroach.  photo by Bart Drees
             Cockroaches have flattened bodies and can crawl through spaces as little as 1/8 inch.  Their elongated, spiny legs allow them to move quickly across the floor.  I have had to make several attempts when trying to step on one because of their ability to move fast, they can be very elusive.  Because they are most active in the dark, you usually see them find their way into your home in the evening hours because of their increased activity at this time.
             The American cockroach (also known as waterbugs or palmetto bugs) is the largest cockroach in Texas, can grow up to 1½ to 2 inches long and are usually found outdoors and in nonfood areas of homes.  Both the adult male and the female can fly.  Which is very disturbing when this large insect is seen flying around your home.   Adults are reddish brown and are one of the most common cockroaches in sewer systems.
           How do we go about making sure this insect does not find its way into our home where it can carry off our prized possessions (just kidding folks!).  First, DO NOT go for the aerosol can of bug spray (or in some cases hair spray, cabinet cleaner,  or spray deodorant, yes, you know who you are!!!) and chase it around the house.  Swatting it or stepping on it is the most effective way of removal.  Then pick it up (I know “ugh!”) in a paper towel or tissue and toss in the trash can.   
            There are things you can do to reduce the chance that his insect will even find its way into your home.  The main thing is removing things from around the home that may serve as a great nesting location for this insect.  Look for dark, moist areas close to decaying organic food sources. 
Cockroaches can live in compost piles, ground cover plants, hollow trees, mulch, old stumps, palm fronds, woodpiles, sewer manholes, and underground water meters.  We can’t do much about, sewer manholes, and underground water meters, but we can reduce the movement of the insects from these locations close to our homes by reducing the possible nesting areas around the home.

What can be done?
  •  Move potted plants away from the house
  •  Do not rest items up against the house, store them appropriately
  •  Move woodpiles, mulch bags  to the back of the lot
  •   Do not mulch up to the house, and remove unused bags of mulch from beside the house 
  •   Repair holes in screens
  •  Plug weep holes in brick homes with copper mesh (a copper mesh wash pad works well)
  •  Repair gaps around doors and check threshold seals under doors
  •  Make sure that roof soffits are screened
  •  Check for gaps around windows and window seals, wall boards and repair/caulk
             If all of the above is done and you still see this insect in your home. Place sticky traps in various places around the home to see where the insect is the most abundant.  Bait stations are available for large cockroaches.  Place the stations against walls, especially around doors and other suspected entry points as identified by the sticky trap.
      As an addition, an insecticide spray can also help manage outdoor cockroaches or treat them in garages and home utility areas.   A good general ready-to -use insecticide can be purchased from a local retail outlet to spray around the house (Usually 3 foot up the exterior wall and 4 foot out from the wall).  Please follow label directions when using any pesticide.  Do not misuse.  Spray suspected cockroach nesting sights and entry points such as building perimeters, doors, soffits, and water boxes.  In garages and utility rooms, spray the room edges and places that are unlikely to be contacted by children or pets.  I prefer the use of an insecticide spray but a granular insecticide labeled for outdoor insect control may also be used to place a barrier around your home.  

     An excellent publication published by my counterpart, Wizzie Brown, in Travis County addresses cockroaches and can be found at this link: Cockroach Biology and Management

     Here is a lengthy video on the cockroach showing an American Cockroach, uploaded by  backyardbugs to YouTube.

Wednesday, July 11, 2012

Rasberry crazy ant in urban gardens!

     I am concerned with what I observed at the Harris County Precinct 2 Master Gardener’s Genoa Friendship Gardens.  The Rasberry crazy ant [Nylanderia sp. nr. pubens (LaPolla, et al)] was observed nesting (larvae, pupae, and workers, and queens) in the leaves circling the shank of the corn ear.  This is the first time I have seen this ant nesting in a growing plant.  I have seen the ant crawling over plants but not actually nesting on the plant.


Rasberry crazy ant nesting on corn plant

Rasberry crazy ant nesting close to corn ear shank

Rasberry crazy ant under corn leaf
Rasberry crazy ant queen with worker ants on corn leaf
      For those of you not familiar with this ant, in 2002, Tom Rasberry, a professional pest-management provider from Pearland, discovered a population of a new pest ant near Pasadena, Texas, in Harris County. Huge numbers of this new ant literally covered the landscape in industrial parks and residences.  So the name has nothing to do with the raspberry but the name of the discoverer.    

     The Master Gardener’s commented that when some of the corn ears were being harvested the ant would emerge from the ears and run all over the arms of the one harvesting the ears.  This ant does not sting, though a slight bite may be felt with no after affects as compared to the painful sting of the red imported fire ant (Solenopsis invicta).  The person harvesting was constantly wiping their arms to remove the ant, and sometimes wiping their neck and face.

     One Master Gardener believes that the presence of the ant reduced the production of their corn plants but as mentioned on the Texas A&M Center for Urban Entomology web page devoted to the Rasberry crazy ant (RCA), “No information is available on potential yield effects in infested lands.”  There is no replicated data that would support this observation but there is information from the Global Invasive Species Database web page that in St. Croix Nylanderia pubens (very close relative to the RCA) has been blamed for crop damages due to high densities of plant feeding Hemiptera (aphids, mealy bugs, scales) that this ant has been observed tending.  The RCA feeds on the honeydew produced by these insects.

RCA tending aphids and feeding on drop of honeydew
Video of Rasberry crazy ant feeding on oak aphid honeydew

     I did observe a high number of aphids and a few mealy bugs under the corn leaves surrounding the ear that the ants could be tending.  Further observations/research on this would be enlightening.

Aphids on corn ear
Mealy bugs on corn ear
      My concern is with gardens in urban areas and other community garden projects that are present in urban areas where heavy populations of RCA are present.  First, the potential for the increased numbers of honeydew producing insects such as aphids, mealy bugs and scales will exist.  The ants protect these honeydew producing insects from other predators.   Second, movement of produce out of the garden areas would just be another avenue to spread the ant.  This could place urban garden projects in jeopardy.

     No testing has been done on products to control the RCA in gardens.  I would recommend that any attempts to control the RCA in garden areas should begin with procedures to limit the number of honeydew producing insects on garden plants.  These procedures may involve one or more of the following, 1) washing or wiping the insect off, 2) removal of infested parts, 3) using insecticidal soaps/oils, or 4) use an insecticide labeled for the specific insect and finally, 5) destruction of the plant may be necessary if the population of these plant feeding insects is too high.  Reducing the population of these honeydew producing insects may help in keeping the number of Rasberry crazy ants on garden plants to a minimum.

     If you do have this ant in your gardens, no matter what control procedures you use to keep the number of honeydew producing insects down,  wash all the produce before removing from the garden.  Corn should be shucked so as not to transport ants hiding within the leaves.  As the picture shows, queens can be present, and if you move a queen you move a population.  Be careful with these ants.

     For more information on the Rasberry crazy ant [Nylanderia sp. nr. pubens (LaPolla, et al)] and other urban insects please visit the Texas A&M Center for Urban Entomology web page.  For general information on the Texas A&M Department of Entomology please visit their web page.