By Hillel Aron
By Joseph Tsidulko
By Patrick Range McDonald
By David Futch
By Hillel Aron
By Dennis Romero
By Jill Stewart
By Dennis Romero
”They‘re swarming now, as a defense mechanism,“ says Greenberg. ”They can actually sense the carbon dioxide in our breath.“
In other words, they can feel us watching.
A mature colony of fire ants will typically consist of 200,000 to 400,000 workers, with a queen who produces up to 800 workers per day. It is generally thought that a colony of ants exists entirely for its queen, but this is not necessarily the case with fire ants. The queen emits pheromones that make her attractive to her workforce, and probably induce them to feed her, but if the overall working environment is not right, the workers may turn on the queen and kill her. Early research in the South, for example, showed that if more than one colony inhabited a confined area, the workers from each colony would join forces and execute the extra queens until only one was left. In the 1970s, however, multiple-queen colonies were discovered, and they are now the predominant type found in Texas. No one is sure why this transformation occurred -- perhaps it is an evolutionary adaptation spurred by human efforts to control the insects -- but it is certainly one of the characteristics that contributes to the fire ant’s invincibility there. As long as one of the queens survives, so does the entire colony.
Few arguments can be made in support of encouraging the survival of the fire ant. It nests inconveniently in walls and attics, under rugs, even in clothes drawers. It restricts outdoor leisure. It destroys longleaf pine seedlings; damages farm equipment and secondary roads by excavating soil; feeds on quail, wood ducks, spoonbills, barn swallows, lizards and the eggs of just about any animal. For reasons unknown, it is attracted to electricity, often shorting out fuse boxes, switches and air conditioners.
On the other hand, fire ants do sometimes benefit agriculture. In Texas, they are known to feed on the boll weevil, a parasite found in cotton plants. They also prey on the Lone Star tick, a serious threat to cattle. And in Louisiana, one of the states hit hardest during the early years of poisonous treatment, farmers now welcome the fire ant because it feasts on sugar-cane bores.
In its native Brazilian ecosystem, the fire ant is far less aggressive and numerous, and consequently is not perceived as a threat. This is partly due to the fact that humans and fire ants have been acquainted with one another for much longer there, but also because the fire ant has at least one significant natural enemy in Brazil. A tiny insect called a phorid fly likes to hover behind the ant and, in a split second, lay an egg on the back of its neck. The larva grows and feeds on the ant‘s brain until the head pops off. Research has shown that fire ants fear phorid flies and avoid traveling from the nest when the flies are nearby. In a lab at the University of Texas, a biologist raises phorids and releases them in designated areas as a control technique. The California Agriculture Department is not considering the use of phorid flies, because as a natural management device it would undermine the agency’s insistence that total eradication is possible.
The fire ant will doubtless always be classified as a pest in North America because it has very few natural enemies here. Biologists call it a ”weed species.“ During his quarter-century studying the insect, a Walter Tschinkel has noted that the fire ant thrives in precisely the areas from which we are trying to eradicate it. ”The fire ant is clearly and dramatically associated with ecologically disturbed habitats, created mostly by man,“ Tschinkel says. ”It is abundant in old fields, pastures, lawns, roadsides and any other open, sunny habitats. It shares these habitats with many other ‘weedy’ plant and animal species.“
Tschinkel was neither surprised nor sympathetic when he learned of the recent infestation of the Golden State. ”In California, development is so grotesque,“ he says. ”How should I put it? It‘s eco-crime. They scalp entire mountaintops, and they remove the soil and everything. Then, on big trucks, they roll in huge numbers of species of exotic plants. All the native biota are replaced, animals and plants both. It’s a total eradication of the native ecosystem. I think that‘s the root of it. That is why the fire ant can exist in California. There is no other reason. No other reason whatsoever. Man is the fire ant’s best friend.“
For a long time now, human colonization of uncharted territory has made pests out of ordinary species. At the turn of the century, sweet chestnut trees along the East Coast were virtually wiped out by a parasitic fungus shipped in from Asia, where it was harmless. A Czechoslovakian landowner bought five North American muskrats in 1905; 30 years later, millions of them inhabited Europe. In 1929, a handful of African mosquitoes made it to the coast of Brazil on a French destroyer; within 10 years, a wave of malaria had swept the country and killed thousands of people. ”We are living in a period of the world‘s history when the mingling of thousands of kinds of organisms from different parts of the world is setting up terrific dislocations in nature,“ wrote biologist Charles Elton in 1958.