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The Boll Weevil In Mississippi: Gone, But Not Forgotten

a Printable PDF Version (13 pages)

A boll weevil pheromone trap.

Figure 1. Boll weevil pheromone traps are memorial monuments to one of Mississippi's most important insect pests. Without the pheromone trap, it would have been impossible to eradicate the boll weevil. Pheromone traps are also the most important tool for detecting boll weevel reinfestations. Consequently, Mississippi cotton growers should take care to avoid damaging traps that are being run in their fields.


a

Figure 2. this graph records historical yield losses caused by boll weevils in Mississippi. Note that losses exceeded 5 percent in some years. Yield losses were lowest following unusually cold winters (1983-84 and 1989-90) because such winters result in high mortality of overwintering boll weevils.


The elongated snout of the boll weevil is the key characteristic that many people use to identify this pest. However this elongated snout is a charracteristic that the boll weevil shares with hundreds of other members of the weevil family.

Figure 3. The elongated snout of the boll weevil is the key characteristic that many people use to identify this pest. However this elongated snout is a charracteristic that the boll weevil shares with hundreds of other members of the weevil family.

 


A. A picture of a pecan weevil.
     B. A picture of a billbug.

Figure 4. Both the pecan weevil (A) and the billbug (B) have snouts, but they are not boll weevils.


Characteristics that can be used to identify boll weevils include the faint light strip through the center of the thorax (A) and the two spurs that are present on the large club-shaped segment of each front leg

Figure 5. Characteristics that can be used to identify boll weevils include the faint light strip through the center of the thorax (A) and the two spurs that are present on the large club-shaped segment of each front leg (B). Note that the inside spur is about twice as long as the outer spur.


A.
Picture of feeding punctures made by both male and emale boll weevils.    B. Feeding puncture caused by small caterpillar larvae.

Figure 6. Feeding punctures (A) which are made by both male and female boll weevils, are easily confused with feeding damage caused by small caterpillar larvae (B).

Figure 7. The raised, pimple-like oviposition puncture caused by female boll weevils is a sure sign of boll weevil infestation.

Figure 7. The raised, pimple-like oviposition puncture caused by female boll weevils is a sure sign of boll weevil infestation.

Figure 8. Flared squares can be caused by many different insects, including boll weevils.

Figure 8. Flared squares can be caused by many different insects, including boll weevils.

Figure 9. Detection of a boll weevil larva (A) or pupa (B) is a sign of boll weevil infestation.

Figure 9. Detection of a boll weevil larva (A) or pupa (B) is a sign of boll weevil infestation.

 

Number of Femal Boll Weevils chart

Figure 10. This graph shows the number of female boll weevils that could potentially result after five generations if all progeny from a single female boll weevil survived and reproduced (assuming each female has 150 offspring, half of which are females). While such high survival rates would never occur naturally, this example emphasizes the high reproductive potential of the boll weevil and the need for early detection of reinfestations.

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Figure 11. A boll weevil can complete all four stages of its life cycle in about 3 weeks. There are about five generations per year.

Back to the publication.


By Blake Layton, Ph.D., Extension Entomology Specialist

Mississippi State University does not discriminate on the basis of race, color, religion, national origin, sex, age, disability, or veteran status.

Publication 2294
Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. Joe H. McGilberry, Interim Director

(2M-2-02)