282 



STATE BOAKD OF AGKICULTUKE. 



Fig. 4. 



Fig. 5. 



less than four species of insects tliat were parasitic 

 on the army-worms. Two of them are nearly allied 

 to our common house-fly, which they much resemble, 

 one being nearly as large (Fig. 4) and the other only 

 about half as large. The other two were tiny Ich- 

 neumon flies. These latter insects, after completing 

 their growth in the larva state, in which they much 

 resemble maggots, came forth and spun their small 

 white egg -like cocoons, fastening them either to the 

 caterj^illars or to the plants, and from these issued the tiny Ich- 

 neumon flies (see Fig. 5). So common were these cocoons that I 

 had large boxes full of them sent to me from Monroe, Lenawee 

 and Branch counties. Many supposed that they Avere the eggs of 

 the caterpillars, and asked if they should be destroyed. Of course 

 I returned a vehement no, written in Italics, underscored and fol- 

 lowed by indefinite exclamation points. Were these to be destroyed, the farm- 

 ers' best friends would be sacrificed. The amount of good done and money 

 saved to us annually by these numerous parasites is beyond comjjutation, and 

 if stated would stagger belief. Again, insects as larva never produce eggs. 

 Keproduction is only provided for in the last stage. Is it not time that some 

 of these common principles of animal economy, so well understood, and of such 

 great practical importance, should be tauglit in our common schools, that such 

 costly, unnecessary ignorance should be driven from among us? 



Hence we see why these insects which occasionally come in myriads are usually 

 held in check. They are devoured by those of their own order. Tliat they 

 occasionally come in armies is only to be explained in the fact that these jjara- 

 sitic insects are, by some means not fully understood, held in check. If, as Dr. 

 Fitch's researches seem to indicate, a dry and wet season always precedes such 

 invasions, tlien may it not be true that such seasons are in some way destructive 

 to these insect foes of the army-worm ? 



WnAT SHALL WE EXPECT? 



From the experience of the past, as well as the innumerable parasites of last 

 year, we have every reason to believe that those localities which suffered last 

 year will be exempt from damage next year, and probably for several years. 

 I think we may liope for general exemption, thougli from the great numbers of 

 moths caught at Lansing last fall, I should not be surprised if the plague was 

 felt there next year. Should this prove to be the case, it would be well for each 

 county to trap for moths each autumn, and if the Leuconia unipuncta were 

 unusually numerous, to burn old meadows and marshes the succeeding fall or 

 spring, thus destroying the eggs, 



If it were at all probable that these destroyers Avould continue to come in 

 force, I would proceed to detail the methods to circumvent their mischief. As 

 we have every reason to hope to the contrary, I will only say that a furrow 

 turned away from a field, or, better, a ditch dug along the side, will detain the 

 caterpillars, so that by firing a winrow of straw heaped above them we may 

 practice a very excusable, and quite as desirable kind of cremation. 



We have here a graphic picture of the noble work wrought by our insect ben- 

 efactors, and I am sure that it has not entered into the mind of man to conceive 

 the length and breadth of tlieir good work. Were it not for beneficial insects 

 and birds, our world would soon be a barren waste and uninhabitable desert. 



