Synonyms and other taxonomic changes
Epeira thaddeus - Hentz 1847
Explanation of Names
Patronym for Dr. Thaddeus Wm. Harris, a great friend of Hentz.
The lattice like retreat is a key identifier of the species.
They also build two different types of orb web. One is the regular type, and the other is the Zygiella x-notata type, which can be seen on pg. 61 of the golden guide. The retreat is always the same, regardless of the web style.
"Observations. This species, which is sometimes whitish on the abdomen, is nevertheless very readily recognized. I have seen some specimens larger than the delineation. Its dwellingplace is really beautiful; it is placed above its web, and made of the finest white silk, shining with a satin lustre; its shape is that of an inverted thimble, and it is usually placed under a leaf bent together for the purpose of affording shelter and security." Nicholas Marcellus Hentz, M.D. 1847
Utah and southern Manitoba to northern New York and Massachusetts, south to Arizona and central Mexico. (1)
The female of this species can be confused with the white form of A. detrimentosus, but the venter markings are different. A. thaddeus venter looks like this:
Males are known to be confused with A. pegnia. A. pegnia males have a median apophysis with two apically directed teeth while A. thaddeus has three teeth of variable size.
The Spider Book by John Henry Comstock
Fifth printing 1980
The Spiders Of The United States by Nicholas Marcellus Hentz, MD
Occasional Papers Of The Boston Society Of Natural History II 1875
(1) Small Orb-Weavers of the Genus Araneus North of Mexico, Herbert W. Levi, 1973.
The Orb-weaving Spiders of Canada and Alaska - The Insects and Arachnids of Canada Part 23 by Dondale, Redner, Paquin, & Levi.