o48 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



PARASITES. 



"Reaumur mentions a parasitic fly which sometimes hatches from 

 grains containing the caterpillars, or pupae, to the number of twenty 

 from one insect." (Curtis.) 



" Mr. Owen has made the interesting discovery, that the larvae of the 

 wheat-moth are sometimes preyed upon by still smaller larva?, which, 

 having destroyed their victims, are transferred to minute black ichneu- 

 mon-flies. These have not yet been obtained from any of the samples 

 of the infected wheat or corn that have come under my notice; but, from 

 the figures given of them by Mr. Owen iu The Cultivator, for November, 

 1846, they appear evidently to be Chalcidian parasites, and belong 

 perhaps to the genus Pteromalus. Of these parasitical Hies he remarks 

 that ' some farmers had noticed large numbers among the tailings of 

 the winnowing machine.' Where they prevail, they doubtless con- 

 tribute, in no small measure, to check the increase of the moths.' 7 

 (Harris.) 



Eecently Mr. F. M. Webster, of Normal, 111., forwarded to Mr. How- 

 ard for determination specimens of a Pteromalus which he had bred 

 from the larvae of the Angoumois Moth. This species, in all proba- 

 bility, is dilferent from the parasite bred by Beaumur, but may very 

 possibly be identical with the insect figured by Mr. Owen. It cannot 

 well be characterized except in connection with a careful study of the 

 genus, which neither we nor Mr. Howard have yet had time to make. 



REMEDIES. 



The problem of a complete, satisfactory, and, at the same time, inex- 

 pensive remedy for this insect, is rather a difficult one to solve. So 

 long as the Southern planter must leave his corn standing in the field 

 all through the fall and main part of the winter, while the more impor- 

 tant work of cotton picking and ginning is going on, he must expect- 

 that when it is finally harvested both the Angoumois Moth and the grain- 

 weevils {Calandra remotepunctata and C. oryzw) will already have gained 

 an entrance to the ears. It remains, then, to kill the insects in the grain 

 when housed or just before storing it away, thus putting a stop to fur- 

 ther damage by these individuals and lessening by so much the numbers 

 of the succeeding broods. With this view many experiments have been 

 made in France, and costly machines have been constructed to accom- 

 plish the desired end. The machine of M. Marcellin, Cadet de Vaux, 

 consists of a large iron cylinder similar to a coffee- roaster j the grain 

 placed within and kept revolving at a uniform temperature of 60° li. 

 [167° F.] for fifty minutes, when it is withdrawn. All larvae, pupae, and 

 eggs are thus killed; the grain undergoes no fermentation, and its germ- 

 iuative power is uninjured. Dr. Herpin, finding that a violent shaking 

 or concussion of the grain will also destroy the eggs and even the con- 

 tained larvae, invented an agitator or shaking machine {tarare) furnished 

 with wooden or iron wings, propelled at a velocity of 600 times a minute. 

 For the invention of this machine, the cost of which was 500 francs 

 ($100), Dr. Herpin received the gold medal of the Societe Imperiale 

 et Centrale d' Agriculture, and also the first-class medal of the Universal 

 Exposition of 1855. 



A much simpler and less expensive plan than this will, however, be 

 found in the adoption of a sort of quarantine station in the shape of a 

 large and tight bin in which corn or wheat could be temporarily placed 

 while the insects are destroyed by some one of several agents. In case 



