Arthropoda means “joint-footed” in Latin and describes arthropods’ jointed bodies and legs connected to a chitinous exoskelelton.5 The majority of arthropods are benign to humans and environmentally beneficial. Some clinicians regard bites and stings as inconsequential and more of a nuisance than a threat to life. However, some spiders have toxic venoms that can produce dangerous, painful lesions or significant systemic effects. Important clinical syndromes are produced by bites or stings from animals in the phylum Arthropoda, specifically the classes Arachnida (spiders, scorpions, and ticks) and Insecta (bees, wasps, hornets, and ants) (Table 118–1). Infectious diseases transmitted by arthropods, such as the various encephalitides, Rocky Mountain spotted fever, human anaplasmosis, babesiosis, and Lyme disease, are not discussed in this chapter.
TABLE 118–1.Insects and Other Arthropods That Bite, Sting, or Nettle Humans |Favorite Table|Download (.pdf) TABLE 118–1. Insects and Other Arthropods That Bite, Sting, or Nettle Humans
|Arthropod ||Description |
|Honeybee (Apis mellifera) ||Hairy, yellowish brown with black markings |
|Bumblebee and carpenter bee (Bombus spp and Xylocopa spp) ||Hairy, larger than honeybees and colored black and yellow |
|Vespids (yellow jackets, hornets, paper wasps) ||Short-waisted, robust, black and yellow or white combination |
|Schecoids (thread-waisted wasps) ||Threadlike waist |
|Nettling caterpillars (browntail, Io, hag, and buck moths, saddleback and puss caterpillars) ||Caterpillar shaped |
|Southern fire ant (Solenopsis spp) ||Ant shaped |
|Spiders (Arachnida) black widow, brown recluse ||Body with two regions: cephalothorax and abdomen; eight legs |
|Scorpions (Centruroides) ||Eight legged, crablike, stinger at the tip of the abdomen; pedipalps (pincers) highly developed (not a true insect) |
|Centipedes (Chilopoda) ||Elongated, wormlike, with many jointed segments and legs; one pair of poison fangs behind head |
Arthropoda comprises the largest phylum in the animal kingdom. It includes more species than all other phyla combined (Fig. 118–1).5 At least 1.5 million species are identified, and half a million or more are yet to be classified. Araneism (pertaining to spiders) or arachnidism (spiders including other arachnids) results from the envenomation caused by a spider bite. “Bites” are different from “stings.” Bites are defined as creating a wound using the oral pole with the intention for either catching or envenomating prey or blood feeding,96,195 or for the purpose of feeding such as in arthropods that have mouthparts for chewing or sucking (plant sucking). “Stings” occur from a modified ovipositor at the aboral pole that is also able to function in egg laying as in bees and wasps. In scorpions the sting is not a modified ovipositor and the “tail” is not a tail but the metasoma section of the abdomen. Stinging behavior typically is used for defense. Most spiders are venomous, and the venom weakens the prey, enabling the spider to secure and digest their prey. However, there is one family of spiders, Uloboridae, which do not have a venom ...