Asian Spiny Backed Spider from Hawaii

Spider, I think
February 10, 2010
Saw another one just like this about twenty yards away. Both in spider webs. So I think it’s a spider. Date was Friday, February 5, 2010. Weather clear. WHAT IS THIS???
Robert Lutman
Heritage Gardens, Wailuku, Maui, HI.

Asian Spiny Backed Spider

Hi Robert,
This is a spider, and more particularly, it is an Orbweaver, though we are not certain of the species.  We will continue to research this unusual find.  Additional research on the Hawaiian Bugs page of BugGuide revealed that this is a species we receive with great frequency, Gasteracantha cancriformis, the Crablike Spiny Orbweaver, though we have never seen this color variation.  Perhaps it is specific to Hawaii, where an isolated population may have diverged noticeably from its closest relatives on the mainland.  The more commonly seen color variations are posted to BugGuide, which indicates additional common names for this species:  “Spinybacked Orbweaver, Crab Spider, Spiny Orbweaver Spider, Crab-like Orbweaver Spider, Crab-like Spiny Orbweaver Spider, Jewel Spider, Spiny-bellied Orbweaver, Jewel Box Spider, Smiley Face Spider
.”  We rarely doubt BugGuide, but in this case we were having problems, so we decided to continue to research this spider by searching for the species in Hawaii.  We found an Organisms of Hawaii website that included another member of the genus, Gasteracantha mammosa, and those photos posted online are a direct match to your spider.  The Insects of Hawaii website lists this species as the Asian Spiny Backed Spider.  The Guide to Common Singapore Spiders refers to this species as the Double Spotted Spiny Spider.  The Hawaiian Biological Surveys section of the Bishop Museum Website also calls Gasteracantha mammosa the Asian Spinyback Spider, and indicates it is native to India and Sri Lanka, and that it was introduced to Hawaii in 1985.  The museum gives it a “bad guy” frown face because of its non-native status, and indicates:  “This spider is more harmless than it looks. It builds a typical spider web but can cause some annoyance to those who accidentally walk into their webs that are strung up across trails and in between trees. It is uncommon on O`ahu because of the introduced red-vented bulbul (also from India), which is its natural predator. In Hawai`i, the bulbul (see card no. 26) is found only on O`ahu.

5 thoughts on “Asian Spiny Backed Spider from Hawaii”

  1. This was really useful as I had run into this spider (its web!) on the Big Island in HI and couldn’t find someone who could tell me its name, species, etc. The ones I found on large orb webs outside the entrance of where I was staying are darker in color — more black — but otherwise exactly the same. As my sister commented, they look like Balinese masks. Thanks!

  2. Far as I can tell, the name G. mammosa was synonomized with G. cancriformis, and this spider is still called that on a number of sites. However, it appears that that is incorrect, because this species has been separated and elevated to its own genus. The correct name, now used by the reputable scientific websites, is Thelacantha brevispina.

  3. Found one at our new home on Oahu I couldn’t believe it was a spider because it stayed in the middle of its web curled up. I wish I could post a picture because the spines on this spider is cool


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