Dysderid Spiders
Order: Araneae
Family: Dysderidae
Scientific Name: Dysdera crocata
Over
fifty species representing the family Dysderidae are found in Europe;
however, only one species Dysdera
crocata occurs in North America.
This species, which lacks a common name, is cosmopolitan in distribution
in the United States.
Many professionals either encounter these spiders trapped on glueboards
or when submitted by clients.
Occasionally, encounters with live specimens result in human envenomizations,
much like a bee sting.
Biology and Habits
This spider is classified as a primitive hunter and weaver. A small, oval cell is spun out of silk and serves as a retreat for this solitary spider. Prey is captured mostly at night without the aid of a silk web. Their chelicerae (front jaws) are long and terminate with prominent fangs. The chelicerae project forward, enabling them to effectively capture live prey such as insects and other arthropods.
The female adults range in size form 11 to 15 mm whereas the smaller males range from 9 to 10 mm. Their coloration is very distinctive: the legs are orange brown, the cephalothorax (the head and thorax) is a dark orange brown, and the soft abdomen is gray.
Adults have six small eyes placed well forward on the cephalothorax. The coxae (the first leg segment) of legs I (first pair closest to the head) and II are cylindrical, as wells longer and thinner than those of legs III and IV. The eight legs terminate with two inconspicuous claws. The body is sparsely covered with hair.
This spider’s mouth parts are also distinctive. The labium (lower lip) is longer than it is wide. The chelicerae have a row of short, stout hairs. The pedipalpi (leg-like appendages behind the chelicerae and in front of the foremost legs) are half the length of the walking legs.
A fertilized female deposits eggs inside a silken retreat. After egg hatch, the spiderlings stay near the retreat until maturation, feeding on live prey.
These
spiders seek dark and humid microhabitats, such as beneath stones and
leaf litter.
They are commonly found near buildings.
Although they prefer the outdoors, these brightly colored spiders
are often carried indoors on firewood or equipment such as leaf rakes.
Control
Since Dysdera crocata has been implicated in human envenomization, avoid coming in direct contact with live spiders. Of all the common spiders inhabiting urban environments, only a few species are of medical importance. As professionals, PCOs need to familiarize themselves with the identity of these spiders.
Dysderid spiders are mainly found outdoors, and therefore prevention should be the first line of defense. Remove leaves, stones and other debris which provide optimal habitats for spiders. Closely inspect and then assess the spider population. If needed, barrier treatments in habitat areas reduce spider populations as well as their insect prey populations. Wettable powders, and microencapsulated and dust formulations are suitable for this type of treatment. Check the product label prior to application.
Occasionally,
these spiders wander or are carried into buildings at night while foraging.
Glueboards may catch these arthropods, and vacuums are effective
in removing them from a building.
(Courtesy of the National Pest Control Association.)