QUESTION:

The ground is moving with Caribbean crazy ants. I have never seen anything like this. After identifying, monitoring and scouting I need control action guidelines. Do you have any suggestions on what to do next?

ANSWER:

Thisinvading ant species has proven to be a challenge, in part because of theoverwhelming numbers that it provides to us. It is given the scientific name ofNylanderia pubens, and is similar to other "crazy" ants we have in the U.S. with its single node, long antennae, and extremely rapid movements. It isnative to islands in the West Indies, but has been in southern Florida since at least1953. A more recent invader appeared in the Houston area of Texas around 2002,and is dubbed the Rasberry Crazy Ant, and this species is also giving humansfits with it massive numbers and highly active behavior. The exactidentification of the Rasberry Crazy Ant is still not determined, but it is aclose relative of the Caribbean Crazy Ant if not the same species. Currentresearch suggests that the Caribbean and Rasberry Crazy Ants are the samespecies, but slightly different geographic races.

Theproblem is not any immunity the ants have to current insecticides, but insteadis the sheer numbers that they occur in. They so overwhelm an area that eventhough millions may die there are millions more to take their place. One PMPreports he commonly finds them inside oak trees that have hollow interiors fromrot, and treating within this void causes major numbers of the ants to emergequickly, but hours later they are still emerging. The pesticides easily killthe ants on contact, but there are too many ants to affect them quickly. So farthe Rasberry Ant is still confined to southeastern Texas and the Caribbeanspecies still confined to the south half of Florida, but living things have away of expanding their range. Not a lot is known about their specific biology,but it appears they have colonies with multiple queens, increasing theirpotential to replace lost workers. They nest in almost any available place,feed on both proteins and carbohydrates, and forage in wide trails of thousandsof workers.

TheUniversity of Florida continues to work on developing an effective controlstrategy for this ant, as Texas A&M is also doing with the Rasberry Crazy Antin their state, but some of the standard IPM practices can be offered to atleast reduce the problems in landscapes and homes. Trimming vegetation awayfrom the exterior walls of structures reduces pathways into the home, creatingbare strips around the immediate perimeter of the foundation helps keep theants further away and maximizes the efficiency of any pesticides applied, andremoval of unnecessary clutter on the soil reduces nesting sites. Keepinglandscape plants free of pests such as aphids or scale insects reduces thehoneydew that these ants crave.

Atthis time even the university suggests that pesticides are necessary, althoughnot the perfect answer. In some feedback from PMPs in south Florida there issome promise using synthetic pyrethroids for their repellent action, and pyrethroidsof most kinds have given some relief from the ants for several weeks. The useof these as a perimeter treatment around structures may provide a "buffer zone"that lasts for a month or longer. There also has been good kill of the antsusing the non-repellents such as Termidor or I Maxx Pro, although completeelimination of nests and colonies does not seem to be happening yet. Baitinghas met with limited success so far, even though the ants do seem to feed oncarbohydrate baits. One suggestion that was offered was the use of the newerproduct Transport GHP, which received great label expansion in early 2008, withgood uses now for ant control around the exterior of structures. This isanother of the non-repellents and may be worth giving a try. The newerTransport Mikron has also given some PMP's good results on these ants, alongwith the use of Talstar granules where labeled.

Themost up-to-date information from Texas A&M and from University of Floridatell us that the magic wand for this ant still does not exist. They suggest theuse of contact insecticides sprayed as a perimeter application aroundstructures and along trails the ants are using. This can be followed byplacement of sugar baits that are replaced regularly to keep them fresh andacceptable. Removal of all potential harborage sites on a property will help tolimit the presence of the ants, and this will be anything on the soil,including piles of landscape debris, boxes, lumber, etc. 

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