Scorpions

Florida scorpions

Extension agents enjoy office visits from local residents bearing gifts in glass jars and plastic containers.  Once in a while the specimens can get a bit creepy.  A recent visitor to our office brought in a small brown lobster-like creature with a curled up tail.  Most folks would have no problem identifying this as a scorpion – the subject of this week’s column.

Yes, Virginia, Florida has scorpions.  However, according to University of Florida Extension Entomologists, none of them are able to produce a fatal sting.  Most folks would view these occasional invaders as a nuisance, and want to know how to control them.

In Florida, encounters with life-threatening non-native scorpions are possible only in the movies or as a result of stowaways or released exotic pets. Of 90 US scorpion species, only four occur east of the Mississippi River.  And, only one of the 90 domestic scorpions, which usually live in the southwest, can kill people. There are about 1,300 species of scorpions worldwide.

Scorpions vary in size from one to four inches long.  These crab-like animals are dark brown, have a broad flattened body.  Like all arachnids, they have only eight legs.  In  front of these true legs are the appendages with the “pinchers”, the pedipalpi, or palps for short.  These have the claw-like pincers which are used to hold their prey.  

Their most noticeable feature is their curled fleshy tail.  It is usually held over their body.   It ends in an enlarged upturned tip that ends in a stinger. The sting is used for defense as well as for capturing prey.

Scorpion venom is a nerve poison, but the dose injected usually is not enough to kill adults. While no Florida scorpions are capable of inflicting a lethal sting, those that have had scorpion stings report that it is very painful, probably more so than a wasp sting.  Scorpions rarely sting humans except when pinned against the skin, such as under clothes or when trapped in bed sheets.  The site of the sting may be sore and swollen for some time.  An antivenin is available for severe reactions to scorpion stings, so medical attention is a good idea.

Florida Scorpion species

According to UF Entomologist Lyle Buss, our office visitor was a Florida bark scorpion, sometimes called the slender brown scorpion(Centruroides gracilis).  It is the largest of Florida’s three scorpion species.  The smallest and most common Florida scorpion is the Hentz striped scorpion (C. hentzi), which is found statewide except the southernmost Keys.  The third Florida species is not found in south central Florida: the Guiana striped scorpion (C. guianensis) is intermediate in size between the other Florida Scorpions and crawls only around Collier, Miami-Dade, and Monroe counties.

A scorpion-like arthropod that is also found in Florida is not a scorpion.  This creature is called a Vinegaroon or Whip-scorpion.  It does not sting or bite, but can spray a caustic "spray" of  acetic acid if disturbed.  It preys on insects that are pests in and around homes, and should be considered beneficial.  Photo:  R. Mitchell, UF/IFAS

Scorpions like to hide outside under boards, rubbish, or other areas that provide shelter and protection. They are a nuisance especially in recently built homes. These predators are active at night, and do their share to reduce pests in and around the home.  Another interesting feature about scorpions is that they glow under ultraviolet lights – so get out the black lights to help track them down.

In the home, scorpions are most likely to be found where they find their food sources: insects, spiders, or similar small animal life. Termites are suggested as the best food source for captive Florida Bark Scorpions. Be cautious when crawling under a house or up in the attic.  And taking care of these other pests will often eliminate scorpions as well.

Scorpions have a long life cycle, lasting three to five years. Males and females go through a courtship ritual prior to mating. Scorpions do not lay eggs and the young are born alive. After birth the young scorpions climb on the back of the mother and remain there until after their first molt.  Scorpions will readily eat their own species and females will often eat their own young.

Here are a few other ideas to make your Florida home and yard less attractive to scorpions and their prey:

• Prune branches so they do not overhand the home, and keep shrubs from touching the outside walls.

• Place trash piles and trash cans on blocks or logs to keep them off the ground.

• Ducks and chickens will eliminate most scorpions from around a building. 

• During dry weather scorpions can be attracted and trapped by spreading moist burlap on the ground around infested areas.

• Keep firewood outside until it is ready to be used, and use gloves when moving it.

• Maintain screens, and use caulk to seal cracks, and seal door openings with weather-stripping.

• In case of a heavy infestation, perimeter residual pesticide sprays can be used as a last resort.

If you encounter a scorpion, the natural reaction is to kill it.  Physical force will do the trick, but be prepared with a quick carefully aimed stomp with a heavy boot.  Glue boards may also be helpful in capturing both scorpions and their food sources without pesticides.

However, pesticides may sometimes be needed for Scorpion control.  Pesticides must come in contact with the animal to work. After applications are made, keep track of how effective the application was in solving the problem. If necessary, reapply according to label directions

Some products effective against scorpions can only be used outside, while others are labeled for indoor use.  Many of these materials may only be used by professionals.  Be sure to use a pesticide only as instructed on the label.  For a list of pesticides currently recommended for Scorpion control by the University of Florida, please review the bulletin, Stinging or Venomous Insects and Related Pests.  Lambda-cyhalothrin is one active ingredient in certain pesticides that is currently (in 2012) labeled for scorpion control, but be sure that any product used is labeled for the kind of location where the application is made.  Read and follow all labels directions!