This article was submitted by Ed Coleman and is Halloween appropriate!
The “Pumpkin” Spider
Few spiders showcase October’s
fall colors more than the marbled orb weaver (Araneus marmoreus). Often called
the “pumpkin” spider because of its relatively large round abdomen, which can
range in color from yellow to orange.
The unique marbling pattern on the abdomen combined with an orange head
and black and white banded legs make this particular member of the genus
Araneus visually stunning.
The marbled orb weaver is very
common, ranging throughout North America.
Habitat preferences are deciduous trees in moist forests along stream banks. However, the marbled orb
weaver can be found in home gardens, shrubs, and tall grasses as well. As an orb weaver, this spider weaves new
symmetrically round webs each day to capture prey. Prey usually consists of flies and small
flying insects. Webs include an
ingenious signal thread which vibrates to alert the spider when pray has been
captured. The signal thread runs from
the center of the web out to the the spider’s retreat. Retreats are usually made of folded leaves
bound together with silk. Although the
marbled orb weaver builds a retreat, this spider is most often observed hanging
out in the center of its web. When threatened, the marbled orb weaver will
usually drop to the ground and hide.
Photo by Ed Coleman
Photo is of a female marbled orb
weaver (Araneus
marmoreus). Females range in size from 5/16 to 13/16 of
an inch. Males are about half the size.
In October, the female “pumpkin”
spider lays orange eggs in a flat silk sac. Eggs sacs are located near the
retreat for protection by the mother and contain several hundred eggs. While the mother marbled orb weaver will die
at the first hard frost, her eggs will over winter in the silk cocoon. Hatchlings, which are also orange, emerge in
the spring and reach adulthood by July.
Poisonous or venomous? Well, as a fellow Master Naturalist recently
reminded me, “all spiders are venomous, but they are only poisonous if you
eat them.” While the marbled orb
weaver can bite humans, its venom is only effective on its pray. Humans may notice a bite mark, but the
marbled orb weaver does not inflict serious injury.
Article by Ed Coleman, Virginia
Master Naturalist, Southwestern Piedmont Chapter
References:
https://infinitespider.com/big-orange-spider/
https://extension.psu.edu/marbled-orbweaver-spider
https://www.insectidentification.org/insect-description.php?identification=Marbled-Orb-Weaver
https://mdc.mo.gov/discover-nature/field-guide/marbled-orbweaver
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