30 
FOREST AND STREAM 
January, 1918 
CULTIVATING SILKWORM GUT AT HOME 
THE CONCLUDING ARTICLE ON OBTAINING TROUT LEADERS FROM FAMILIAR CATERPILLARS 
EXPLAINS FULLY THE PROCESS OF MATURING THE WORMS AND DRAWING THE GUT 
By EDWIN T. WHIFFEN 
W HILE I have been writing and you 
have been reading, the caterpillars 
have been feeding and growing. In 
a week or so, the worm has developed suf¬ 
ficiently to be ready for the second moult. 
The process of resting, cessation from 
feeding, and shedding of skin is repeated. 
After this moult, the color is distinctively 
yellow, and the larger tubercles are ap¬ 
parent. The worms should now be thinned 
out, some in each cage being transferred 
to another. Always be sure that the new 
receptacle is clean when used. Remember, 
the conditions of success are two: perfect 
cleanliness, and sufficient food of a proper 
kind. Under these conditions the cater¬ 
pillars thrive like young chicks. After a 
somewhat longer period of feeding—and 
they will keep you busy gathering leaves— 
they moult for the third time. At this 
stage their heads are green with black 
markings. The bodies have become yel¬ 
low 7 , and have two rows of black dots run¬ 
ning from “stem to stern.” The large 
black, red, and yellow tubercles might 
cause them to be thought in the final stage. 
But the} 7 now crave more food than be¬ 
fore, and fairly cram themselves with the 
leaves supplied to them. At this stage be¬ 
gin feeding the leaf suited to insure the 
very best quality of gut. I have found 
this to be, first, fleshy, juicy leaves from 
the plum tree, and, a close second, the 
prickly leaves of the long blackberry, 
which the caterpillars munch down with 
much gusto. You ought to have left, in 
spite of accident, disease, and death, at 
least half or two-thirds of your hatching, 
some two hundred or so healthy and flour¬ 
ishing crawlers. Listen, as they eat, after 
you have put in fresh leaves for them in 
the morning; the sound will remind you of 
a gentle fall of rain in summer. 
I F they ate before, they cram, gorge, dis¬ 
tend, stuff themselves now. In a week 
or ten days, they should be ready for 
the final moult. They then emerge hun¬ 
grier than ever. Their color is much as 
before, but the size of the head seems 
enormous. In a week or ten days more, 
they have grown four or five inches long, 
and very plump and sleek. Then they 
cease feeding, and prepare for the impo*- 
tant process of spinning. First they empty 
the digestive system entirely, excreting a 
thick, syrupy fluid. Up to this time, the 
excrement has been fairly firm, and the 
marked change in consistency is a indica¬ 
tion that spinning may be expected soon. 
It is a good plan, during the last stage, 
to put worms out of doors to feed, select¬ 
ing the most suitable food-plant for them. 
I have thought that the gut produced by 
this treatment w r as of superior quality. 
Whether that idea is fancy or fact may be 
debatable; but this I do know, it is much 
easier for the one who has the job of 
looking after it to bring the worm to its 
fodder than to bring its fodder to the 
W'orrn. They may grow somewhat larger 
in this way, as there is never any lack of 
food; whereas those reared in cages, espe¬ 
cially at this stage, eat so fast that they 
need feeding two or three times a day, 
instead of only once, as during the pre- 
A healthy and flourishing crawler 
vious moults. In this stage, and especially 
when I had large numbers, I have some¬ 
times used small branches with their 
leaves, in Mason jars containing water. I 
found a tendency on the part of the cater¬ 
pillars to crawl down after a drink and 
so drown themselves. My usual method 
of feeding has been to put the loose leaves 
(cut or torn on the edges, when the cater¬ 
pillar is small) right into the cage, and 
change food at least once a day. Some 
labor can be saved by using the plan I de¬ 
scribed above of putting the twigs with 
leaves into bottles or jars containing water. 
But, to prevent the untimely loss of some 
of your “star boarders,” wind wool or 
tie cotton around the twig just above 
•where it enters the neck of the bottle or 
jar, so that all suicidal intentions may be 
frustrated. I once matured a brood of 
cecropias by means of the “branch and 
bottle” method, on the top of a square 
piano. The jars tipped over sometimes, 
and the water ran dowft into the “inwards” 
of the instrument, but it was only the 
piano that suffered—the worms thrived. 
W HEN you find the soft, fluid excre¬ 
ment in the cage, you may know 
that one or more of the caterpil¬ 
lars will soon begin to spin. The worm 
shortens somewhat, as the body-cavity con¬ 
tains little except the empty digestive sys¬ 
tem and the sacs with the fluid silk. These 
are two long, transparent tube-like organs, 
each about eighteen inches long, about the 
diameter of a steel knitting needle, curi¬ 
ously coiled and involved in the body cav¬ 
ity. At their front ends they connect with 
small tubes, or spinnerets, th'rough which 
the caterpillar forces the fluid silk in shap¬ 
ing the material with which it spins. The 
spinning process is an interesting one. The 
caterpillar crawls restlessly around, seek¬ 
ing a suitable place. At such a time, a 
short film of silk may be seen hanging 
down from its mouth. If you want to 
keep some cocoons over winter for the 
next season, put the prospective spinner 
by himself into a glass receptacle with a 
few leaves, and watch proceedings. 
After satisfying itself that it has se¬ 
lected a suitable place, the caterpillar firmly 
grasps a twig with the false legs, or props, 
and with the true legs on the forward part 
of the body pulls the ends or sides of 
leaves together. Then the head moves up 
and down, back and forth, a film of sticky 
silk gripping the leaves and holding them 
together. The worm works industriously, 
and soon the general outline and size of 
the cocoon appear, half-hidden in the 
leaves. In a few hours, the caterpillar 
has spun sufficiently to hide itself from 
sight. If you wait a week or so, and then 
carefully open an end of the cocoon, you 
will see an interesting sight. In place of 
(continued on page 46) 
