common name: common house spider
scientific name: Achaearanea tepidariorum (C.L. Koch) (Arachnida: Araneae: Theridiidae)
The common house spider, Achaearanea tepidariorum (C.L. Koch), may be the most abundant of
the several species of spiders that live in the company of man in the southeastern United States,
especially in Florida. Although Archer (1947) thought that A. tepidariorum was less common
inside houses than Pholcus phalangioides Fuesslin (Pholcidae) in Alabama, he also noted its
abundance.
adult
Levi (1967) considered A. tepidariorum to be a cosmopolitan species. Although the species was
first described from Germany, it appears to be native to South America, judging from the
numerous similar relatives which occur there. It is abundant in Central America and Mexico, and
occurs as far north as southern Canada (Levi 1955). It has been recorded from most of the
contiguous United States (Levi and Randolph 1975). The species probably now has a worldwide
distribution, having been carried around the world by man on plants. Although A. tepidariorum
belongs to the same family (Theridiidae) as the notorious black widow spiders (Latrodectus spp.),
it is not known to be dangerous to humans. One case of serious allergic reaction to the bite of A.
tepidariorum is known from Gainesville, Florida.
This species was known for many years under the name Theridion tepidariorum. Archer (1947,
1950) created a new genus Parasteatoda for a group of species that Levi (1955) later considered
to belong to the genus Achaearanea.
Carapace and sternum are yellow to brown, legs are yellow to brown with darker rings; the
abdomen is higher than long, is gray with black and white pigment, and has a white spot behind
the highest point, surrounded anteriorly by black with dark lines running down the sides and black
chevrons behind; the venter has two light patches enclosing a darker area; the male is darker and
smaller than the female; females range from 5 to 8 mm in length, while males are generally about 4
mm in length (Levi 1955, 1967).
female
male
The species most likely to be confused with A. tepidariorum is Tidarren sisyphoides
(Walckenaer). However, T. sisyphoides has a distinctive white stripe on the posterior part of its
abdomen, and it forms a sort of "tent" out of a dead leaf in the middle of its web under which it
hides.
Females and juveniles make typical theridiid webs (tangle webs). These webs are frequently made
between two adjoining edges of a building, for example, between an eave and a wall. Many
individuals may occur in the same area and build nearly contiguous webs covering large areas of
eaves, wall space, and window frames. Webs may be built both inside and outside of buildings;
when inside, they are frequently a major contributor to the build-up of "cobwebs." Sheds, privies,
barns and stables, in addition to dwellings, may have heavy populations of this species. Other
characteristic habitats include undersides of highway bridges and culverts. It is largely absent in
wild situations except around entrances and in chambers of eaves, on dry mountain ledges, and on
dry ledges of river bluffs (Archer 1947).
A. tepidariorum feeds on a variety of prey, including German cockroaches and scorpions (Archer
1947; pers. obs.). While awaiting prey, spiders are usually positioned in the middle of their webs,
but resting individuals may be nearer a lateral or upper edge of the web, where the complex color
pattern on the spiders' bodies near the substrate may help camouflage them against some enemies.
Frequently males may be seen hanging in webs of adult and subadult females. A single female,
may produce many pear-shaped light brown eggsacs during the year, which are hung freely in the
web. At least in Florida, all stages seem to occur throughout the year.
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Archer AF. 1947. The Theridiidae or comb-footed spiders of Alabama. Alabama Museum of Natural History Paper 22: 1-67.
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Archer AF. 1950. A study of theridiid and mimetid spiders, with descriptions of new genera
and species. Alabama Museum of Natural History Paper 30: 1-40.
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Levi HW. 1955. The spider genera Coressa and Achaearanea in America north of Mexico
(Araneae: Theridiidae). American Museum Novit. 1718: 1-33.
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Levi HW. 1967. Cosmopolitan and pantropical species of theridiid spiders (Araneae:
Theridiidae). Pacific Insects 9: 175-186.
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Levi HW, Randolph DE. 1975. A key and checklist of American spiders of the family
Theridiidae north of Mexico (Araneae). Journal of Arachnology 3: 31-51.
Author: G.B. Edwards, Florida Department of Agriculture and Consumer Services, Division of Plant Industry.
Originally published as DPI Entomology Circular 279.
Photographs: Jeff Lotz, Division of Plant Industry; and Jim Kalisch, University of Nebraska - Lincoln
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-238
Publication Date: September 2001
Copyright 2001 University of Florida
Featured Creatures
Department of Entomology and Nematology
Division of Plant Industry
Electronic Data Information Source