Received from:
Dr. Roberto Pereira
rpereira@ufl.edu
and
Dr. Philip Koehler
pgk@ufl.edu
BLDG. 970
University of Florida
Gainesville, FL 32611

In recent weeks, several reports on tiny stinging flying ant outbreaks have come to our attention. Samples have been sent from Polk County with reports of ants landing on people and stinging them. Most recently, we have had a report from Volusia County, and an unconfirmed report that flying stinging ants caused a Florida resorts to close.

Although we have not seen sample from all these occurrences, the samples we have examined were from an ant from the genus Hypoponera. The ants we examined were 2.5 to 3 mm long, with dark brown bodies and light brown legs. They were winged females, possibly Hypoponera opacior. Another species in the same genus, Hypoponera punctatissima, is known to sting people all over Florida. Pictures of these species can be seen at http://www.antweb.org/.

These ants live in natural areas and the encounters with humans are probably due to mating flights that occur after rain events. It is not clear why these ant problems are being reported in higher numbers this year than any previous years. It is possible that for some reason, the number of nuptial flights and the number of ants involved in these nuptial flights are up this year. A possible explanation is the dry weather earlier this year, causing the delay in nuptial flights, concentrating them in a shorter period of time. Also, it is possible that these ants, like many others, naturally produce a varying number of alates each year depending on weather conditions and many other factors.

Interestingly, Hypoponera ants reproduce both by wingless and winged reproductives. Wingless reproductives mate in the nest (in some cases, males will mate with females that are still in the cocoon). Winged alates fly away from the nests before mating. These different mating and reproductive strategies may not occur in the same colony. Hypoponera ants are unusual because the alates (reproductives) sting people, as opposed to other ants (fire ants for instance) where worker (wingless and flightless) are the ones stinging. The stinging incidents are likely to go away when no more alates are available to fly from their nests. Application of control measures is probably unnecessary. Anyway, due to the difficulty of locating nests, and the distribution of nests in natural areas away from the residences and businesses, controlling these ants cannot be done very effectively.

Like other natural phenomena, the unusually high numbers of stinging ants seen this year, most likely will not repeat every year. Having said that, for unknown reasons, different ant problems seem to be on the rise in recent years. Here in Florida, we do have to learn to appreciate a bit of the natural creatures that we are "blessed" with. It certainly beats shoveling snow for 4 months straight. These stinging flying ants have been bad enough to cause outdoor activities to be cancelled. We must keep an eye on this problem and see if it persists. If that it is the case, perhaps control measures can be attempted, but for now, the best thing to do is to enjoy the cooler air indoors, and let the flying ants enjoy their mating flights outdoors.