NEST MAKING: ITS ORIGIN AND USE. 331 
governing all creatures and all their actions, has developed in certain ar- 
thropods the habit of spinning tubes or cylinders as a protection to the 
body. 
Among the spider fauna this habit is particularly prominent. It does 
not exist, as with insects, in a larval state, but in the perfect animal, the 
only one, with possibly one exception, of which we have knowl- 
edge. The belief has been expressed that both sexes of the Pso- 
cidee possess the power of spinning a web which McLachlin affirms is not 
distinguishable from that made by spiders.2, This habit, which character- 
izes the larvee of insects, is carried forward to the perfect animal among 
the Aranes, and, as we have seen, the habit of protecting themselves by 
tubular spinningwork, in one form or another, exists among some spe- 
cies of every tribe of spiders. 
One who is conversant with insect architecture cannot but be struck 
with the resemblance between the nests of spiders and those made by the 
larve of certain insects. Brief allusion has already been made to this, but 
it may be worth while to call attention more distinctly thereto. 
Very often I have met, along the seashore in New Jersey, a species of 
leaf roller Tortricid moth, whose species I do not know, that has reminded 
me of the nests of Epeira trifolium spun among the ferns, and 
Epeira which is one of the most beautiful examples of the nesting habit 
ae Moth ty be found among spiders. The two objects may sometimes be 
arva, ‘ : 
seen almost side by side, and even the most casual observer 
would scarcely fail to note that they must have been constructed upon the 
same fundamental principles of architectural instinct. There are, of course, 
differences which one may note without very acute perception; but the 
resemblances are certainly worthy of consideration, and it is to these that I 
have here wished to call attention. (See Figs. 316 and 317.) 
The nest of Theridium riparium is constructed on very much the same 
principle as that of the larva of the caddis fly, or case worm, a Neurop- 
terous insect which is very well known, and whose remarkable 
Theridi- architectural habit has excited the interest of naturalists, Sev- 
a ee eral illustrations of the nests of this insect are given.’ The first 
dis Fly. Tepresents a case made of bits of moss, and is the work of Lim- 
nophilus rhombicus. (Fig. 323.) The second represents the case 
worm, found in great abundance by Professor Packard in Labrador, and 
which he supposes to be the work of Limnophilus subpunctulatus, the 
most abundant species found in Labrador. The case is straight, eylindri- 
cal, and built of coarse gravel, and the larva is a thick, cylindrical, whitish 
worm. ‘The next figure (Fig. 320) represents the nest of Limnophilus 
Psocidee. 
* Psocus sexpunctatus. See a note of the author in Proceed. Acad. Nat. Sci. Phila., 1883, 
page 278. 
* Monograph British Psocidee, Entomological Monthly Magazine, Vol. IIT, 1866-7, page 268. 
* These are copied from Packard’s “Guide to the Study of Insects,” page 617. 
