16 BULLETIN 416, U. S. DEPARTMENT OF AGRICULTURE. 
they are at hand, but that impregnation occurs but once. Von Han-— 
stein (1902), writing of a European form, records many details which 
agree with those exhibited by the American form. Males are often 
observed waiting on quiescent deutonymphs, which they excitedly — 
stroke and overrun, as though trying to assist in the molting process. — 
A typical case of copulation may be described as follows: The female, 
issuing from her deutonymphal skin is immediately attended by one — 
or more males. The female remains comparatively quiet and the 
male crawls directly under her from behind. The legs I of the male 
are reached up around the hind portion of the female’s abdomen, and 
the tip of the male’s abdomen is then bent sharply upward and slightly 
forward (fig. 4) until the genital aperture of the male comes in con- 
tact with the vulva, which is subterminal. At the approach of a sec- 
ond male the engaged individual usually ‘‘backs out” from under the 
Fic. 4.—Outline sketch of male red spider, showing the characteristic copulatory attitude with reflexed 
abdomen. (Drawn with camera lucida,175.) (Original.) 
female and upon the departure of the intruding male resumes his for- 
mer position. 
Parthenogenesis.—Perkins recorded that females readily deposit 
eggs upon failure to mate and that from these unfertilized eggs only 
males develop. He also states that, after producing a number of 
eggs, if impregnated subsequently, such females produce a majority 
of female eggs. Banks (1900) says that the first eggs laid by unfer- 
tilized females ‘‘ produce only males, which, when adult, will pair with 
the females, and the latter will then lay eggs producing both sexes.” 
Morgan determined that eggs from unfertilized females were viable 
and capable of development. Ewing reared to adult 52 eggs of three 
virgin females and all of them became male. 
While it has been known that unfertilized eggs become male indi- 
viduals, no effort has been made, apparently, to test the potency of 
agamic males. Upon a few occasions parthenogenetic males have 
been isolated with virgin females, which deposited the usual number 
