104 



TRANSACTIONS OF THE ILLINOIS 



from day to day as they issued from peaches that were thrown into 

 another vessel, and in due time the parasitic flies began to issue from the 

 ground along with the perfect Curculios. Nay more than this, I soon 

 learned to distinguish such Curculio larvte as were parasitised, and after 

 they had worried themselves under the ground — seldom more than half 

 an inch — I would uncover them, and on several occasions had the satis- 

 faction of watching the gnawing worm within reduce its victim until 

 finally nothing was left of him.* As soon as the Curculio larva is de- 



[FlGURE 5.] 



a. d ^ 



Sigalphus Curculio Parasite : (a) larva ; {V) cocoon ; (c) pupa. 



stroyed by the parasite, the latter (Fig. 5, a) encloses itself in a tough 

 little yellowish cocoon of silk (Fig. 5, ^), then gradually assumes the 

 pupa state (Fig. 5, c) and at the end of about the same length of time 

 that the Curculio requires to undergo its transformations and issue as a 

 beetle, this, its deadly foe, gnaws a hole through its cocoon r .id issues to 

 the light of day as a black four-winged fly (Fig. 4, a, male; h^ female). In 

 the vicinity of St. Louis, this fly was so common the past season that, 

 after very careful estimates, I am satisfied three-fourths of all the more 

 early developed Curculio larvse were destroyed by it. On the 17th and 

 1 8th of April, in that locality a severe frost killed the peach buds on all 

 but a few of the young and most vigorous trees of Hale's Early and 

 Crawford, so that instead of a large and abundant crop of peaches to 

 depredate on, the little Turk had to concentrate its attacks on the few 

 peaches that were left ; and no one expected that any fruit would be 

 saved. Yet the work of this little parasite was so effectual that, wher- 

 ever fruit set, a fair crop was gathered even by those who made no effort 

 at all to protect their trees ! 



While visiting Dr. Fitch last August, at his house in Salem, N. Y., I 

 compared my bred specimens with his species, and found them identically 

 the same; but I shall, in this reading, omit the description which 

 follows and which may be read, by those interested, when this essay is 

 published. 



As Mr. Walsh bred this same pararsite from the larvas of his little Plum 

 Moth, it doubtless attacks other soft-bodied larvae and does not confine 

 itself to the Plum Curculio. This is the more likely as it would scarcely 

 pass the winter in the fly state. The female, with that wonderful instinct 

 which is exhibited in such a surpassing degree in the insect world, knows 

 as well as we great Lords of Creation what the litde crescent mark 

 upon a peach or plum indicates ; and can doubdess tell with more surety, 

 though she never received a lesson from her parents, whether or not a 



