18 



TOBACCO-WOn«. nAB A SECOND PAKASITB. REMEDIES. 



And after tliese flics have left llieir cocoons, it is readily told by the 

 appearance of cacli cocoon, whether it is a Microgaster or a Pteromalus 

 fly whicli has come out from it. The Microgaster, by which all the cocoons 

 are constructed, makes an opening for its escape in a more neat and 

 artistic manner than does its destroyer. When it passes from its pupa 

 state and awakens to life in its perfect form, it finds itself closely pent up 

 within its narrow cell — so closely that about the only motion it is able to 

 make is to turn its head from side to side. And it discovers that by grasp- 

 ing with its jaws the wall of its cell, it is hereby able to gradually roll 

 itself over in its bed. And now, with the minute sharp teeth at the ends 

 of its jaws, it cuts a slit transversely through tlie wall of its cell, lengthen- 

 ing this slit more and more as it gradually turns itself around. Thus it 

 cuts the end of its cocoon smoothly off in the form of a little lid, a few 

 ursevered fibres being left on one side, which serve as a hinge to hold 

 this lid in its place. The inclosed fly then pressing its head against this 

 lid raises it up and crawls forth from its prison. Thus the evacuated 

 cocoon has its end smootlily cut off, with the severed portion usually ad- 

 hering to it. The Pteromalus fly, on the other hand, being a size smaller, 

 is able to move about and can probably turn itself around inside of the 

 cocoon. And to make its escape it gnaws a hole through the side near 

 one end, of sufficient size for its body to pass through; this hole in different 

 instances being round, oval, or irregular, and its edges ragged and uneven. 



In addition to the eggs of the Microgaster, which are inserted under the 

 skin of the Tobacco-worm and thus are not visible externally, I have 

 occasionally met with a worm having one or more eggs glued upon its 

 surface, usually placed in a crease of the skin to render the attachment to 

 ■ ii more secure. These eggs are about three-hundreths of an inch long 

 and a third as thick, oval, white, smooth and glossy like enamel. Within 

 them a minute soft white worm or maggot becomes formed, which is 

 hatched by gnawing through the shell of the egg at one end, and as it is 

 coming out, it sinks itself downward through the skin of the worm and into 

 its body, a blackish dot upon the skin near the end of the empty egg 

 marking the point where it has entered. Its history I have not been able 

 to trace further than this. The facts show it to be another parasite des- 

 troying the Tobacco worm, and that it is probably a two-winged fly belong- 

 to tiie order Diitera. 



The remedies for this insect are remaining to be spoken of. But as we 

 have had no personal experience in combatting it, it will not be expected 

 that we dwell upon this branch of the subject at any length. 



The leaves of the potato and tomato being of no value, the presence of 

 this worm upon them is wholly diregarded, as its limited numbers never 

 consume the foliage to such an extent as to perceptibly diminish the growth 

 of the tubers in the one or of the fruit in the other of the plants. But 

 with the tobacco it is very different. The whole value of this plant depends 

 upon its leaves; consequently every morsel which this worm consumes from 

 them is a loss, and if the leaves are much eaten the loss is great. The 

 utmost vigilance is therefore required to save the tobacco from injury from 



