60 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 
is parasitic on Epeira diademata and also upon supposed spider cocoons ; 
Pezomachus fasciatus is guest within the egg nests of Agreeca brunnea, and 
on a species of Theridion; Hemiteles similis parasitizes Epeira diademata 
and an unknown spider cocoon. Hemiteles rufocinetus, H. fulvipes, and H. 
formosus are reported as body parasites, while other species of the genus 
are parasitic upon spider eggs. This generalization appears to me remark- 
able, and contrary to what one would naturally suppose from the ordinary 
specialization of such instincts. If correct, it shows much elasticity of 
habit among these parasitic Hymenoptera, for there would seem to be an 
immense distance on the maternal side between the instincts which prompt 
to the several acts; and on the side of the offspring, between development 
within a spider’s egg and within a spider’s body. 
Mr. Howard, who was kind enough to look over this part of my manu- 
script, expresses the doubt here suggested in a more positive way. He thus 
writes me: “None of the spider Pimplas are typical, but belong to a 
restricted group, possibly a subgenus, all of which, I believe, are parasitic 
in spider egg bags. All of the Polysphincta, in my opinion, are ‘external 
parasites of spiders; and this genus, with the genus Acrodactylus, I believe 
contains all of the external hymenopterous spider parasites.” This opinion 
from such an authority would justify the omission of the above inference ; 
but as the facts as reported are not changed in Mr. Howard’s published 
lists, I permit the item to remain as qualified. The observations of early 
date which here compose the list are probably erroneous; and, indeed, 
they are confessedly defective. 
Fourth, the general spinning and other characteristics of spider species 
appear to make no marked difference in liability to parasitic attack. Such 
sedentary spiders as Epeira, Theridion, and Agroeca are not exempt 
Relations from body parasites by their occupation of snares. Yet, in such 
of Spin- F : : re 
ine cases, one wonders how the ingenuity of the insects’ maternal 
Habits. instinct could overcome, as we know it does, the local difficulties, 
and drop an egg upon the spider’s body while swinging upon or 
lurking within its web. The difficulty is not lessened, but rather enhanced, 
if we suppose that some of the parasitic larve are traveling parasites, and 
seek their hosts after independent hatching. The condition of the wingless 
female parasite would appear to make her task more formidable, but does 
not limit her ovipositing to periods when the spiders are off their snares 
and reposing on adjacent objects, or within their dens and tents. 
Fifth, the special cocooning habits of spiders appear to have no relation 
to their exposure to parasitic attack. Here, also, one meets apparently con- 
tradictory facts. For example, the egg cocoon of Argiope 
Of Co-  gophinaria is one of the most skillfully constructed to protect 
she rie the enclosed young. (See Vol. II., pages 76-80.) The eggs are 
encased in a silken sheet, overlapped by a thick, compact oval 
blanketing, which in turn is encased in a tough glazed sac. The whole is 
