infestation. We selected 24 locations at the edge of the prairie and the woods, each 25m
apart. Each location was randomly assigned to either a crazy ant colony addition
treatment or control. Prior to establishing treatments, we baited for ants on June 17,
2009, following the same protocol used in all subsequent baitings. At each location, we
placed two 9cm diameter Petri dishes; one dish contained a ~2gm slice of Libby’s Vienna
Sausage, and the other dish held a cotton ball soaked with 30% honey water. We
monitored each Petri dish for 10 minutes or until it was discovered, at which point we
recorded the ant species and the number of minutes that had passed since opening the
bait. One hour after baits were opened, we closed the Petri dishes and placed them in a
freezer until the number of each species in each dish could be recorded.
Five ant species were collected during the initial baiting: Solenopsis invicta (17
dishes), P. sp. nr. pubens (8 dishes), Solenopsis sp. cf. geminata (3 dishes),
Crematogaster sp. (1 dish), and Pheidole sp. (1 dish). Solenopsis invicta was the most
commonly collected ant species and had the highest average recruitment with 153.2 ants
per dish. Crazy ants recruited to a total of 7 locations: to sugar baits at 5 locations, to
protein at 1 location, and to both sugar and protein at 1 location. The average crazy ant
recruitment was 25 ants, and all but the 2 protein baits had 12 or fewer crazy ants.
On June 19,2009,12 crazy ant nests were collected in decaying logs from the
high-density infestation area. Collection of superficially similar nests from a different
site in 2008 revealed that these nests often contained more than 3000 workers and at least
5 queens (personal observation, K. Hom). Therefore, while we were unable to measure
the size of the experimental colonies, each colony likely had at least 1000 workers and
more than 2 queens. Because the nests had been collected from a wooded area, we
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