The bite may be painful and may become erythematous. Some people have reported a necrotic ulcer developing at the site.
Criteria for the diagnosis of a hobo spider bite:
(1) definite observation of a spider bite
(2) definite identification of the spider as a hobo spider
(3) exclusion of other causes of the lesion, especially the presence of pathogenic bacteria
Recent research raises questions about whether the venom of the hobo spider can cause necrotic skin ulcers. The venom does not cause hemolysis of human red blood cells (Gaver-Wainwright et al)..
Additional problems in making the diagnosis:
(1) The diagnosis of spider bite may be made presumptively without any real evidence.
(2) Speciation of spiders can be difficult for the novice or inexperienced observer.
(3) The diagnosis of a hobo spider bite may be made outside of its usual geographic distribution.
Features of the hobo spider:
(1) one or more chevrons (V-shaped pattern) on the abdomen that point towards the head
(2) light stripe running down the middle of the sternum
(3) 2 spinnerets extending from the bottom of the abdomen
(4) absence of colored bands where the leg joints meet
(5) absence of distinct longitudinal dark stripes on the top side of the cephalothorax
