23 



green, the large warts or tubercles on the top of the third and fourth segments are coral red, 

 the remainder are yellow excoptins; those on the second and terminal segments, which, in 

 common with the smaller tnbercles along the sides, are blue. During its growth from the 

 diminutive creature as it escapes from the egg to the monstrous-looking full grown specimen, 

 it consumes an immense amount of vegetable food ; and especially as it approaches maturity 

 is this voracious appetite apparent. Where one or two have been placed on a young apple 

 tree, they will often strip it entirely bare before they have done with it, and thus prevent the 

 proper ripening of the wood, entailing damage to the tree, and, sometimes, endangering its Hie ; 

 hence, during their season, they should be watched for and destroyed. During the winter 

 months, their cocoons may be looked for, and removed in time to check their further spread. 



The natural increase of this insect being so great, wise provisions have been made to 

 keep it within bounds. Being such a conspicuous object it sometimes forms a dainty meal 

 for the larger birds ; there are also enemies which attack the egg and young larvae and besides 

 these there are several parasites which live within the body of the caterpillar and destroy it 

 before reaching maturity. One of the largest of these parasites is the long tailed Ophion 

 (Ophion niacrurum, Linn.) Fig. 20 (after Kiley). This is a large yellowish lirowu Ichneumon 

 y^ J, fly, and is perhaps one of the commonest parasites affect- 



ing the cecropia. The female of this fly deposits, ac- 

 cording to Mr. Trouvelot, from eight to ten eggs upon 

 the skin of her victim. These eggs soon batch into 

 young larva; which eat their way through the skin of 

 the caterpillar, and at once begin to feed upon the fatty 

 parts within. As only one of these parasitic larvae can 

 find food sufiScient to mature, the rest either die from 

 hunger or are devoured by the strongest surrivor. 



Mr. Riley, in Am. EnL, Yol II., says, "After 



the Cecropia Worm has formed its cocoon, the parasitic 



larva which bad hitherto fed on the fatty portions of its 



victim, now attacks the vital parts, and when nothing 



but the empty skin of the worm is left, spins its own 



cocoon, which is oblong oval, dark brown inclining to 



bronze, and spun so closely and compactly, that the 



inner layers when separated have the appearance of gold beater's skin. If we cut open one of 



these cocoons soon after it is completed, we shall find inside a large, fat, legless grub. Fig. 21, 



Fio. ■>!. which sometimes undergoes its transformations and is.sues 



as a fly in the fall, but more generally waits until the 



followiu;; Spiiug. 



'• The Ichneumon Fly, last mentioned, usually caur^es 

 a dwarfed appearance of the worm which it infests, and 

 parasitized cocoons can generally be distinguished from 

 healthy ones by their smaller size. The larvae of the Ta- 

 china Fly which we now introduce to our readers, as parasitic on the Cecropia Worm, seem to 

 pi-oduce an exactly op[)osite effect, namely, an undue and unnatural growth of their victim. 

 In the beginning of September, 1866, we received an enormouii Cecropia Worm. It mea- 

 sured over four inches, was a full inch in diameter, and weighed nearly two ounces, butlike 

 many other large .specimens which we have since.seen, it was covered with small oval, opaque, 

 white egg-shells, clusters of four or five occurring on the back of each sesniont invariably 



deposited in a traverse direction. The skin of the worm wa.1 

 black, where the young )iarasites had hatched and penetrated. 

 The large worm soon ilied and rotted, and in al)out twelve days 

 a host of maggots gnawed their way through the putrid skin. 

 These maggots averageil about one-half inch in length, and in 

 form were like tho.se of the common Ulow-fly. The head 

 was attenuated and retractile and furnished with two minute 

 curved hooks, and the last segment wasscpiarely cut off, slightly 

 concave and with the \isual two ai)iraeles or breathing holes 

 which this class of laivie have at their tails. Tlioir colour waa 

 of a translucent yellow, and they went into the ground and 



Fio. 22. 



