OBSERVATIONS ON THE BIOLOGY OF 
ACHAEARANEA TESSELATA 
(ARANEAE: THERIDIIDAE) 1 
By William G. Eberhard 
Depto. de Biologia, 
Universidad del Valle 
Cali, Colombia 
Achaearanea tesselata is relatively common in trees and bushes in 
urban Cali, Colombia (el. 1000 m) and the surrounding country- 
side of the same elevation which Espinal (1968) classifies as a dry 
tropical forest zone (annual rainfall about 900 mm). As it appears 
that nothing is known of the biology of this species (Levi, pers. 
comm.), it seems worthwhile to publish brief descriptions of some of 
its more outstanding characteristics. 
Webs 
The webs were usually isolated, although occasionally several oc- 
curred in a single bush. Each web consisted of a horizontal, more 
or less circular platform, with thick mesh above and thin mesh 
below (Fig. ia). A piece of leaf or other detritus was nearly al- 
ways suspended in approximately the middle of the mesh above the 
sheet, and the spider rested within or just below this object. Usually 
the shelter was a curled leaf, and spider rested inside, out of sight 
from above or the side. No consistent differences were noted be- 
tween webs of small and large spiders. 
When the web threads were coated with fine powder (corn- 
starch) and then blown and jolted, all the powder came off, thus 
demonstrating that none of the web threads were sticky. Although 
the platform portion of the web did not have an obviously regular 
structure, there appeared to be some limits to the diameters of the 
holes beween threads (Fig. ib). 
The spiders were capable of building a more or less complete web 
in a single night, but were occasionally found on incomplete webs. 
One morning after a very strong rain in the night which almost cer- 
tainly destroyed all webs, several spiders were found on webs with 
both mesh and platform of clean, apparently new threads, but one 
thank Dr. H. W. Levi for identifying specimens and furnishing addi- 
tional information. This study was supported by a grant from the Fondo 
Universitario para la Investigacion of the Universidad del Valle. 
Manuscript received by the editor March 1, 1972. 
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