660 REPORT UNITED STATES GEOLOGICAL SURVEY. 



reached them, and I feel safe in saying to yon that in a circle of ten miles from Worth- 

 ington there will scarcely be an egg left by to-morrow night. I send you a bottle 

 herewith containing the cones and the parasites. Wo could scarcely find % cone, or 

 sack, except as they were indicated by the parasite on tho surface ; and each cone 

 ■which was not entirely destroyed had from five to fifty of the red laborers at work 

 upon tho eggs. We found scores of cells with no eggs left except the shells. As fast 

 as tho bug finishes one cone, it s(arts upon an expedition for new worlds to conquer, 

 and it instinctively finds and conquers the new world. I, of course, informed our 

 station-agents and others at Ileraby and Heron Lake of this discovery, and they also 

 promised to make a thorough investigation, as I will do hero, and the results will be 

 reported forthwith. If the matter is general, deliverance is nigh. » » » i stopped 

 for fifteen minutes one and a half miles west of Wilder, where Section-Foreman Smith 

 took me to that portion of his farm where eggs were deposited. We could find none 

 by general digging; but wherever we found, as we frequently did, the red parasite on 

 the surface, we found the cone beneath, with the parasite at work consuming the eggs. 

 * * * I am aware that two years ago this parasite was found working upon the 

 eggs at Madeira and other places, but here we have the remedy almost as soon as the 

 eggs are laid, while in the former instances the parasite was only discovered in the 

 spring." 



It is bright red and oblong oval, as seen in the engraving. The Tachina 

 fly {Tachina ationyma Riley) attacks the locust, depositing one or more 

 eggs in the back, at the insertion of the wings. The young of the fly is 

 a large white maggot. (See Plate LXIII, Fig. 3a, for the maggot of a 

 Bimilar fly.) 



Description of the Tachina maggot. — The following description is based on three speci- 

 mens received from Mr. A. Whitman, of Saint Paul, Minn., and said by him to have 

 been taken from the body of a grasshopper {C. spretus). The body is flattened, cylin- 

 drical, tapering suddenly toward each end, the head-end being more pointed than the 

 opposite extremity. The segments are quite distinct, with raised ridges. The head is 

 minute, one-third as wide as tho segment behind, with two black hooks, i. e., the man- 

 dibles. The larvae of the genus lack the little slender tubercles forming tlie rudi- 

 mentary antennae and mouth parts seen in Anthomijia and Miirca. Length, .35 inch. 

 The egg is said by Riley to be "oval, white, and opaque, and quite tough." 



It is this fly probably which attacks the locust in the Western Terri- 

 tories, and I may add to the accounts of its habits given by Professor 

 Riley (Seventh Report, p. 178), the following statement in a letter from 

 Lieutenant Carpenter, dated Camp Robinson, iS^ebraska, December 27, 

 187G: 



I have often observed a fly, about the size of the Idow-fly, of a greenish mottled color 

 with the abdomen tipped with red, annoying Culoptenus spretus. It would light on 

 the ground just behind the grassliopper, and the in.stant it took wing would pounce 

 upon it, and the two roll over and over on the ground struggling for several moments, 

 •when the fly would release the grasshopper. I have caught them both in this act, and 

 upon examination of the grasshopper, always found the little red eggs on the body. 



This fly is said by Riley to be common and destructive to the grass- 

 hoppers. Mr. Whitman writes me regarding its occurrence in Minne- 

 sota as follows: "I have opened six hundred and twenty-four grass- 

 hoppers {q)retns} ; nine of these contained grubs (of the Tachina fly prob- 

 ably) and ten had hair-worms." 



The locust-cggeating maggot. — Another fly which is very useful from 

 its habit of devouring the eggs of the locust is the Anthomijia radicum 

 var. calovteni of Riley^. It is quite similar to the onion-maggot and 

 radish-fly, both in its maggot and winged states. I have received sev- 

 eral of the maggots from Mr. Whitman said to have been found among 

 the eggs of the locust. I give the following description of them ; 



Larva of Anthomyia radicum calopttni (Plate LXIII, Fig. 2). — Body long and slender, cyl- 

 indrical, soft, elongate-conical, tapering gradually toward the minute head ; the seg- 

 ments are not very convex ; beneath they are thickened to take the place of feet. Tlie 

 antenniB and maxilli© form slender pointed tubercles much as in Musca domestica. Tiio 

 protlioracic spiracles are situated on the hinder edge of the segment, and are remark- 

 ably long and slender. Tho end of the body is full and rounded, flattened conical; the 



