The functional significance of web decorations in orb-web spiders has been an area of intense study for well over a hundred years. Two main hypotheses, (prey attraction and predator avoidance) have had intermittent support and criticism. By varying the decoration pattern, spiders minimize the potential predation costs of constructing a highly visible signal and deter potential prey such as bees from associating decorations with danger. The prey attraction hypothesis implies that as the signal changes, so should the response of the intercepting insects. In this study, I tested the response of bees to varying decoration patterns. I show that stingless bees (Trigona carbonaria) respond to the silk decorations of Argiope keyserlingi Karsch 1878 in similar ways irrespective of the pattern of decorations. I also demonstrate that the likelihood of prey hitting the capture area is greater than that of hitting the hub area in decorated webs. Since stingless bees respond similarly to different levels of signal strength, I conclude that variation in decorations does not affect prey interception.

Aterigena n. gen. is erected for four Palearctic species of funnel-web spiders previously placed in Tegenaria Latreille 1804 or Malthonica Simon 1898 (Agelenidae: Tegenariini) and A. aspromontensis n. sp., an Italian species described here. The following new combinations are proposed: Aterigena aculeata (Wang 1992), A. ligurica (Simon 1916), n. comb. (from Tegenaria), as well as A. aliquoi (Brignoli 1971) and A. soriculata (Simon 1873), n. comb. (from Malthonica). The latter two species were originally described in Tegenaria. The new genus is diagnosed by the unique combination of several morphological character states (e.g., notched trochanters III and IV, lateral spines on patellae, shape of vulvae). The monophyly of the new genus is also supported by a molecular analysis based on CO1 sequences of several taxa. Keys are provided for the identification of the recognized genera of Tegenariini and the species of Aterigena n. gen. Several species of Pseudotegenaria Caporiacco 1934, originally described in Tegenaria, are morphologically close to Tegenaria tridentina L. Koch 1872, a species that is grouped in the cladistic analysis using CO1 in the monophyletic taxon “Tegenaria clade 1”. The species are therefore transferred back to Tegenaria as Tegenaria animata Kratochvíl & Miller 1940 stat. rev., T. bayeri Kratochvíl 1934 stat. rev., T. bosnica Kratochvíl & Miller 1940 stat. rev. and T. decolorata Kratochvíl & Miller 1940 stat. rev. Aterigena n. gen. has an interesting geographical distribution: it is widely disjunct in the Palearctic. Four species occur in the Mediterranean and one in China, respectively. A. ligurica is relatively widely distributed in mainland Italy and adjacent Southern France with a single specimen known each from Spain and Egypt (Alexandria), respectively. The latter may be the result of an accidental introduction. The other three European species are endemic to Sicily, Corsica (perhaps also Sardinia) and Calabria, respectively.

Many studies of the elegant architectures of orb webs are conducted in controlled laboratory environments that remove environmental variability. The degree to which spider behavior in these circumstances resembles that of spiders in the wild is largely unknown. We compared web architecture and silk investment of furrowed orb weavers Larinioides cornutus (Clerck 1757) building webs in laboratory cages and spinning webs on fences in the field and found significant differences. The volume of major ampullate silk in radii was 53% lower in cage webs, primarily because the silk was 50% thinner, but also because spiders tended to spin 14% fewer radii than in fence webs. Cage spiders also invested about 40% less flagelliform silk and aggregate glue in the capture spiral, although the difference was not statistically significant, a trend primarily driven by a decrease in the length of the glue-coated capture spiral. These patterns were consistent with spiders reducing silk investment when building at new web sites while they assessed insect abundance. Differences in the type of substrate for web attachment, amount of available space, and condition may also have influenced web architecture. Cage webs were more symmetrical than fence webs, which displayed an unusual horizontal asymmetry that may have maximized their capture areas within the constraints of the available fence-railing attachment sites. Our findings suggest using caution when generalizing the properties of laboratory-spun webs to more natural conditions. More importantly, they demonstrate that orb spiders actively modify their behaviors when spinning webs under different conditions.

Understanding the variation of diversity patterns requires analysis at multiple spatial scales. In this study we estimated the diversity components (alpha, beta and gamma) of the spider community at El Vínculo Natural Regional Park, using the additive partitioning of diversity (species richness, Shannon's diversity index and Simpson's index) for the first time on this taxon in Colombia. We collected the specimens following a nested sampling design that consisted of two spatial scales. At the local scale, we quantified additive diversity components in 238 sampling units, and at the regional scale in five vegetation types. Total observed regional diversity (γ) was partitioned into its additive components: within sampling units (α₁), among sampling units (β_l) and among vegetation types (β₂). We used the same approach to compare common and infrequent spider species and to compare sampling methods. A total of 1565 adult spiders and 72 identifiable juveniles, including 193 morphospecies from 36 families, was sampled during the study. In all cases (entire community, infrequent species, common species and four different sampling methods) we found that a significant percentage, relative to that of randomization tests, of the diversity measurements used was attributed to beta diversity among vegetation types. The relative contributions of alpha and beta diversity to total observed regional diversity depended on the diversity measurement used. The contribution of beta diversity with respect to alpha diversity was low using Simpson's index (less than 20%), whereas with species richness and Shannon's index the contribution was high (up to 90% and up to 66%, respectively). Our results suggest that beta diversity is the main component of diversity in the natural park. We concluded that the maintenance of a large variety of vegetation types can be an important tool for the conservation of spider richness at the natural park.

Historically Buthus occitanus (Amoreux 1789) was recognized as the sole species of the genus present in the Iberian Peninsula, but recent morphological studies have identified and named two additional species. In addition, molecular data on the Moroccan fauna has shed light on the diversity within the genus. More species have since been described from North Africa, where diversity within the genus is highest. In this study we assessed the genetic diversity within specimens of Buthus Leach 1815 from across the Iberian Peninsula using cytochrome oxidase 1 (CO1) mitochondrial DNA sequences. The known range of B. ibericus Lourenço & Vachon 2004 was greatly expanded, with the species widespread in most of the western part of the Iberian Peninsula. Five distinct mtDNA lineages were found within Buthus from the Iberian Peninsula, two of which were reported for the first time in this study. However, both B. ibericus and B. occitanus included highly divergent lineages and thus further studies are needed to fully comprehend the taxonomy of Buthus from this region.

The Neotropical spider genus Paradossenus is revised and currently comprises a total of 14 species. P. andinus (Simon 1898), P. protentus (Karsch 1879) and P. venezuelanus (Simon 1898) are new junior synonyms of P. longipes (Taczanowski 1874), the type species of the genus. Five known species, P. longipes, P. caricoi Sierwald 1993, P. pulcher Sierwald 1993, P. corumba Brescovit & Raizer 2000, and P. minimus (Mello-Leitão 1940), are redescribed and illustrated. New species: P. isthmus, P. benicito, P. amazonensis, P. acanthocymbium, P. tocantins and P. pozo are described from both male and female. The new species P. sabana is described only from the male while P. junin is described only from the female. The subfamily Trechaleinae is erected, diagnosed, and an illustrated key to all the included genera is presented.

Maternally inherited endosymbiotic bacteria Wolbachia pipientis have been shown to have wide-ranging effects on the reproduction of their hosts. This study presents the first survey and characterization of Wolbachia pipientis that have infected spiders collected from Wuhan, Hubei Province, China. First, we used universal primers of the wsp gene (Wolbachia Surface Protein, WSP) to examine the infection of Wolbachia in spiders. We found that, out of 31 spider species, 7 species were infected with Wolbachia. Then we used the specific primers of the A and B Wolbachia supergroups for the wsp gene to determine if there are super-infections in these infected spiders. Specimens of Nephila clavata were infected with strains of both A and B Wolbachia, while the others were infected with either strain A or B. Lastly, we aligned the sequences obtained with published ones to establish the phylogenetic relationships among Wolbachia found in spiders. The Wolbachia in Larinia argiopiformis Bösenberg & Strand 1906, Eriovixia cavaleriei (Schenkel 1963), Araneus ventricosus (L. Koch 1978), and Pholcus crypticolens Bösenberg & Strand 1906 belong to the A supergroup and the other three species, Nephila clavata (L. Koch 1878), Oxyopes sertatus L. Koch 1877 and Coleosoma octomaculatum Bösenberg & Strand 1906 belong to the B supergroup.

For spiders, morphological differentiation within genitalic traits is the main diagnostic criterion of a species. Beside some well-described exceptions of genitalic polymorphism and crypticity, spider genitalic variation is seldom quantitatively analyzed. Using geometric morphometrics landmark analysis, we report clear evidence of quantitative interspecific divergence and intraspecific variation in the genital shape of three species of the genus Paratrechalea (P. azul, P. ornata and P. galianoae). The genitalic species recognition was very consistent with our quantitative data for both sexes. Interspecific variation suggested a character displacement pattern between two syntopic populations of P. azul and P ornata, and also a possible case of species crypticity in P. ornata that will involve splitting the Uruguayan populations from the Brazilian ones.

The genus Iviella Lehtinen 1967 (Dictynidae) comprises three North American species, I. ohioensis (Chamberlin & Ivie 1935), I. reclusa (Gertsch & Ivie 1936) and a new species from the Northern Peninsula of Newfoundland. We provide a new diagnosis of the genus, describe the new species and describe the previously unknown male of I. reclusa. We also describe or re-describe the intricate copulatory ducts and spermathecae of the three species.

Ground-living spiders of different habitats in the Cabañeros National Park, central Spain, each under different management conditions, were studied to characterize their community richness and composition. Five different habitats were selected: Mediterranean forest, abandoned pine plantations and three kinds of dehesas or meadows (differing in their understory management). In three sampling periods, during two springs and one in fall (2001–2002), a total of 1,152 pitfall traps were deployed in five different habitats. A total of 3,801 adult spiders, representing 105 species from 24 families were collected, among which 13 are considered endemic for the Iberian Peninsula. Correspondence analysis and indicator species analysis showed that spider richness and assemblages differed considerably among the different habitats. The scrub dehesa had the highest ground-living spider richness. Twenty-three indicator species were identified for the different habitats, of which four are considered endemic for the Iberian Peninsula. Gnaphosidae have a high potential as indicators of habitat quality.

Although bromeliads can be important in the organization of invertebrate communities in Neotropical forests, few studies support this assumption. Bromeliads possess a three-dimensional architecture and rosette grouped leaves that provide associated animals with a good place for foraging, reproduction and egg laying, as well as shelter against desiccation and natural enemies. We collected spiders from an area of the Atlantic Rainforest, southeastern Brazil, through manual inspection in bromeliads, beating trays in herbaceous shrubby vegetation and pitfall traps in the soil, to test if: 1) species subsets that make up the Neotropical forest spider community are compartmentalized into different habitat types (i.e., bromeliads, vegetation and ground), and 2) bromeliads are important elements that structure spider communities because they generate different patterns of abundance distributions and species composition, and thus amplify spider beta diversity. Subsets of spider species were compartmentalized into three habitat types. The presence of bromeliads represented 41% of the increase in total spider richness, and contributed most to explaining the high beta diversity values among habitats. Patterns of abundance distribution of the spider community differed among habitats. These results indicate that bromeliads are key elements in structuring the spider community and highlight the importance of Bromeliaceae as biodiversity amplifiers in Neotropical ecosystems.

Ground invertebrates such as spiders react to changing conditions in their terrestrial environments. Due to climate change, changes of species diversity, community composition and ecological traits (e.g., habitat specialization) can be assumed. Since it is often impossible or impracticable to carry out large-scale investigations concerning the impact of microclimate change on soil arthropods, studies on responses of arthropod communities to simulated climate change at a smaller scale may be a useful alternative. I conducted a field experiment to detect potential changes in species richness, community structure and ecological traits of spiders caused by prolonged drought. In a semi-dry grassland/Juniperus communis heath complex, five 16-m² plots were subjected to either a drought (excluding all rain) or non-drought treatment. Activity densities of spiders were measured using pitfall traps from July to September, 2008. Although differences in microclimate between treatments were significant, no significant treatment effect on either species richness or activity densities was found. Ordination analyses (NMDS) and multivariate analysis of variance (MANOVA) revealed no significant difference in assemblage composition between the treatments, nor were any changes in ecological traits detected. Spiders were not a suitable model group for detecting any changes in the present study, but comparable experiments yielded changes for at least some spider families and especially for microarthropods. For future small-scale studies I recommend a multi-species group approach with micro- and macroarthropods, using a broad spectrum of sampling techniques.

A new species of montane scorpion is described from the Sierra Madre Occidental of Mexico. The species is morphologically similar to scorpions distributed throughout the “sky island” region of the southwestern United States and northwestern Mexico and is a member of the “vorhiesi” subgroup of the Vaejovis “mexicanus” group. The morphology of the new species is compared to that of “vorhiesi” subgroup taxa, and biogeographic hypotheses about the diversification of this group are provided.

A review of the pseudoscorpion genus Oreolpium Benedict & Malcolm reveals two species, the type species O. nymphum Benedict & Malcolm 1978 from northwestern USA and O. semotum, new species, from southern Tasmania. Oreolpium is most similar to Neominniza Beier, Thaumatolpium Beier and Teratolpium Beier from South America, and to Protogarypinus Beier from southern Australia. These genera are confirmed as members of Garypinidae, and both species of Oreolpium are found to lack glandular setae on sternites VI–VIII, which is an unusual feature for Garypinidae. Oreolpium demonstrates a remarkable bipolar distribution, similar to that of the pseudoscorpion groups Pseudotyrannochthoniidae, Pseudogarypidae and Syarininae, and to several water mite taxa.

Capturing unusually profitable prey early in life potentially enhances one's future fecundity and survival. Newly emerged crab spiderlings Misumena vatia (Araneae: Thomisidae) occasionally capture prey that greatly exceed them in size. I attempted to evaluate what if any long-term advantage these kills provided by presenting naïve, just-emerged spiderlings with syrphid flies Toxomerus marginatus that exceeded the initial mass of the spiderlings six-fold, a prey that the spiderlings occasionally captured in the field. A second group of spiderlings received a single syrphid initially and subsequently a single fruit fly Drosophila melanogaster every other day, and a control group received a fruit fly every other day. The few spiderlings that regularly captured the syrphids gained significantly more mass than the other groups. Individuals taking an initial syrphid and then fruit flies did not gain more mass than controls fed on solely on fruit flies. Neither did a group of spiderlings followed in the field nor a small group of individuals fed multiple fruit flies every other day in the laboratory differ in growth rates from the syrphid fruit fly or single fruit fly groups. Thus, capture of a single bonanza prey does not provide the spiderlings with a significant advantage over those that did not obtain this reward, and in the field they probably do not manage to duplicate the capture success of the surviving members of the syrphid-only group.

Orientation is an essential process preceding movement behavior. Information necessary for orientation toward suitable habitat can be gathered by acute and internal information. The former comprises directly detectable, external stimuli, whereas internal information includes earlier experienced environmental cues and inherited information related to an individual's origin. In habitats that can suddenly be disturbed (such as river banks), an accurate orientation is of prime importance for successful movement toward safe habitat. In a common-garden field experiment, we studied between-population variation in movement responses toward safe winter habitat (dike vegetation) of two sympatric riparian wolf spiders, the stenotopic riparian species Pardosa agricola (Thorell 1856) and the generalist P. amentata (Clerck 1757). Both responses to direct visual cues and orientation toward home habitat were investigated on an unfamiliar river bank upstream from the original populations. Movement toward safe habitat was mainly controlled by previously collected information on the riverbank location in the stenotopic species and additionally influenced by visual cues and the prevailing weather conditions. Movements in P. amentata were flexible and not systematically guided by either internal information or direct visual cues. Experience on the location of safe habitat consequently guided orientation in the stenotopic species. Internal information is therefore hypothesised to favor the stenotopic wolf spider by restricting unnecessary movements when sudden threatening situations emerge. Generalist species have less experience with the specific disturbance and do not show pronounced orientation capabilities toward safe habitat.

The species classically grouped in the genus Zygiella F.O. Pickard-Cambridge 1902 are thought to all possess a characteristic orb web feature – a spiral-free sector in the upper part of the orb. Zygiella s.l. has recently been split into four genera, Zygiella s.s., Leviellus Wunderlich 2004, Parazygiella Wunderlich 2004 and Stroemiellus Wunderlich 2004, and proposed to belong to family Zygiellidae, rather than the classical Araneidae. To find orb web features that could potentially diagnose these species and/or genera, we investigated female web architectures of L. thorelli, P. montana, S. stroemi, Z. keyserlingi and Z. x-notata. We investigated a total of 278 female webs and compared 16 characters emphasizing web size, web and hub asymmetry, as well as radial and spiral counts. The free sector may be present in all species but its prevalence in female webs varied from 41% in Z. keyserlingi to 94% in P. montana. Various combinations of web architecture characters may diagnose those species that in our sample represented all four genera: Zygiella s.s. may be diagnosed by the median number of non-circulating sticky spirals below hub, Stroemiellus by the small web size with small mesh width and the non-circulating spirals above hub, Parazygiella by few primary radii and sticky spirals, and Leviellus by a pronounced vertical hub displacement. This suite of diagnostic features may provide preliminary support for the current taxonomy of Zygiella s.l., although the ultimate test, i.e., a phylogeny, is needed to test the validity of the genera. Seven out of 16 web characters are potentially phylogenetically informative because they show a statistically significant shared variation among species. Our study, which pioneers the quantification of web data to distinguish species, implies that the interspecific variation in webs may turn out to reflect phylogenetic relationships among Zygiella s.l.

The presence and origin of the mygalomorph spider genus Ummidia Thorell 1875 in the western Mediterranean region is reconsidered. The traditional idea, expressed in the works of Walckenaer and Simon, that Ummidia is a recent American import in the Mediterranean region, is opposed by the observation that at least four distinct Ummidia species inhabit different geographical areas within the western Mediterranean. The taxonomical revision of the Mediterranean Ummidia fauna presented here results in the description of one new species (Ummidia algarve n. sp.), the removal of U. picea Thorell 1875 and U. algeriana (Lucas 1846) from synonymy with U. aedificatoria (Westwood 1840) and the placing of U. occidentalis (Simon 1909) in synonymy with U. aedificatoria (Westwood 1840).

When crab spiderlings Misumena vatia (Clerck 1757) emerge from their natal nests their small resource reserve makes them vulnerable to starvation, while their small size makes them vulnerable to many predators. Choosing substrates that allow hunting opportunities as well as protection from predators may thus be life or death decisions. Here we investigate the substrate choice of crab spiderlings on goldenrod Solidago canadensis and Solidago juncea inflorescences in relation to a frequently encountered predator, the jumping spider Pelegrina insignis (Banks 1892). Flower heads of S. canadensis are smaller and more densely packed on branches of the inflorescences than the heads of S. juncea, but the two species attract similar numbers of small flies, the major prey of the spiderlings and jumping spiders. Crab spiderlings significantly preferred S. canadensis, both in initial choice and length of time occupied, as did their jumping spider predator. However, capture times of spiderlings by small jumping spiders (< 5 mg) did not significantly differ on the two goldenrods, although the preferred goldenrod, S. canadensis, provided superior protection from larger jumping spiders (>5 mg). Thus, although occupancy on the preferred goldenrod does not make spiderlings safer from all jumping spiders, it provides superior protection from large ones and may be the basis for the substrate preference of the spiderlings.

The remarkable bark spiders (genus Caerostris: Araneidae) are poorly known Old World tropical orb-weavers, whose diversity, currently at 11 species, is grossly underestimated. Most species build large webs at forest edges, clearings, and gardens, but in Madagascar, probably the hot spot of Caerostris diversity, at least one species occupies a unique ecological niche: casting its web across streams, rivers and lakes, so that the orb is suspended above water and attached to substrate on each riverbank via bridgelines up to 25 m. Here, we summarize current knowledge on Caerostris natural history, and specifically focus on the remarkable web architecture and biology of the newly described Caerostris darwini n. sp. Darwin's bark spider builds its web, a regular orb suspended above water, and maintains it with daily reinforcing of bridgelines and renewal of orb for many days. Web size ranged from 900–28,000 cm², with the largest measured web of about 2.8 m² being the largest orb ever measured, to our knowledge. With anchor lines capable of bridging over 25 m, it also builds the longest webs among all spiders—a unique form of web gigantism. We report on mass capture of ephemeropteran prey items in C. darwini n. sp. webs during a single day. Webs contained up to 32 mayflies that were subsequently wrapped en masse before the spider fed on them. We also provide the first evidence of kleptoparasitism in these webs both by other spiders (Argyrodinae) and by newly documented, undescribed symbiotic flies. Caerostris display extreme sexual size dimorphism with large females and small males, which is manifested in enigmatic sexual behaviors such as mate guarding, male-male aggressiveness, genital mutilation, mate plugging, and self castration. Caerostris is thus a promising candidate for evolutionary studies, and its diversity, biology, and phylogenetic relationships all deserve a closer scrutiny.

A new species of Trechalea Thorell 1869, T. rothi from Colombia, South America, is described, illustrated and compared with the only other two species of the genus also known from Colombia, T. longitaris (C.L. Koch 1848) and T. lomalinda Carico 1993. Additionally, it is compared with the similar species, T. trinidadensis Carico 1993. A single female from Pará, Brazil, is also described and illustrated as a new species, Enna xingu, based on features of the genitalia.

This paper describes the sexual behavior of Bothriurus buecherli San Martín 1963 and compares it with the rest of the B. prospicuus group. The mating behavior was very similar to other species of the group, but B. buecherli presented some differences in the initial stages, one being a long period of inactivity after the male grasps the female pedipalps. Information presented includes reference to the sexual sting, post-partum copulation, and an analysis of a case of cannibalism by the female.

A new species of the medically important recluse spider genus Loxosceles Heinecken & Lowe 1832 is described from the State of Bahia, Brazil. The species occurs between rocks and crevices, as well as in and around man-made structures. The new species belongs to the gaucho group, as evidenced by the spermathecal shape and color pattern. The presence of a long male palpal tibia is unusual in the gaucho group; thus, the inclusion of the new species in this group is discussed.

The female of Sarotesius melanognathus Pocock 1898 is described for the first time. According to characters of the copulatory organs of both male and female as well as to cheliceral dentition the monotypic genus is placed in the Palystinae Simon 1897.

Published descriptions of egg sac construction behavior in araneids are scarce. We describe egg sac construction and oviposition in one individual of the poorly known araneid Pozonia nigroventris (Bryant 1936) and two individuals of Micrathena sp. These spiders folded dead leaves to protect their eggs. All individuals pulled up and hung a dead leaf above the forest floor, oviposited on the leaf, and then folded the leaf around the egg sac. They then deposited the enclosed egg sac in the leaf litter below. The use of dead leaves in this way probably evolved convergently, since these genera are only distantly related.

We report the first confirmed cases of harvestmen (Opiliones) feeding upon live vertebrates. In June and July of 2007, in two independent studies of the ecology of Swainson's warblers (Limnothlypis swainsonii Audubon) in Arkansas and North Carolina, we recorded predation of nestlings at two separate nests by harvestmen. Both events were nocturnal, involved relatively young and dependent nestlings, and contributed to or resulted in the death of one or more nestlings. One event involved a group of at least four harvestmen with one to four individuals feeding upon a brown-headed cowbird (Molothrus ater) nestling at one time, and the other involved up to two harvestmen present at the nest, but only one individual fed upon the two Swainson's warbler nestlings.

The ribosomal internal transcribed spacer ITS2 is probably the most popular nuclear DNA marker used to examine relationships among and within species in animals and plants. ITS2 sequences have also begun to be used as DNA barcodes. ITS2, however, has rarely been used in studies of spiders. Here, I examine the potential utility of this marker for spider phylogenetics based on preliminary data for Anelosimus spiders and a brief summary of prior work. The secondary structure of ITS2 facilitated alignment of highly divergent sequences and indicated that secondary structure morphology might be phylogenetically informative in itself. Phylogenetic analysis of Anelosimus species was congruent with a prior study based on a combination of six mitochondrial and nuclear loci plus morphology regarding the deeper clades within the genus. However, ITS2 had insufficient variation to resolve relationships within species and among closely related species. Previous studies have also discovered relatively little within-species variation in ITS2. In sum, ITS2 is an easily amplified and sequenced marker that is underutilized in spider phylogenetics; however, it has limited uses at the lowest taxonomic levels and is not likely to be a universally useful DNA barcode marker.

The geogarypid pseudoscorpion Geogarypus irrugatus (Simon 1899) is redescribed based upon the syntype series from Sumatra. All subsequent records of this species from Asia are shown to be misidentifications.

Female lycosids carry their egg sacs on their spinnerets until spiderlings emerge but spiders are occasionally found carrying shells, dirt, or other objects on their spinnerets, suggesting recognition errors can occur. We investigated some proximate cues that may influence egg sac recognition and discrimination in the wolf spider Pardosa milvina (Hentz 1844). We tested the ability of female P. milvina to discriminate among egg sacs based on size, texture, and contrast. We also tested the ability of P. milvina to discriminate between its own or a conspecific's egg sac, and the ability to discriminate between an egg sac that had just been removed and an egg sac that was removed seven days earlier. When given a choice, females significantly chose their own egg sac over plastic beads of equal mass, preferred large plastic beads equal in mass to an egg sac over small plastic beads, round over faceted beads, and showed a non-significant tendency to attach black rather than white beads of equal mass. When given a choice between two conspecific egg sacs, spiders more often rejected those that had been removed from the mother seven days earlier than those that had been freshly removed. Spiders were unable to recognize their own egg sacs versus a conspecific's. Although spiders recognize egg sacs from non-egg sacs based on mass, texture, and presumably odor when given the choice, acceptance of non-egg sacs was common when no real egg sac was available. Also, females would not reattach their own egg sac once an artificial one had been attached. Attachment of any object on the spinnerets apparently ceases searching or attachment behavior.