Western Army Cutworm 



cocoons (Fig. 7, Plate I, Page 11) in which their development is com- 

 pleted. These cocoons are sometimes fastened to the dead worm, 

 sometimes to grasses or other plants, where they cling in clusters. 



Chalcis-fly 



The little Chalcis-fly 4 (Fig. 8, Plate I, Page 11) is one of the most 

 interesting parasites which attack the cutworms. The parasitized 

 worms die before changing into pupae. A single worm killed by this 

 parasite has been known to contain over 2,000 of these little flies. The 

 parasites complete their development in the dead worm. Figure 4, 

 Plate IX, Page 27 shows a parasitized worm just before the emergence 

 of the parasites, the pupa of which completely fill the skin of the cut- 

 worm and can be seen through it as little oval bodies. 



Digger-wasp 



The digger-wasp 6 (Fig. 18, Plate VI, Page 21) is another very in- 

 teresting natural enemy of cutworms. The figure represents one of these 

 insects carrying an army cutworm to its burrow. So interesting are 

 their habits that the writer is giving the story of the capture and sub- 

 sequent entombing of a cutworm by a digger-wasp. 



On warm days in early summer these blue-black wasps can be seen 

 hurrying over the ground, in and out of every hole, under every clod 

 and into every possible place where a cutworm could hide. In its search 

 many short flights are made and when running the wings are jerked 

 nervously, while every movement of the hunter is indicative of the 

 greatest haste. 



When a cutworm is found it is immediately .paralyzed, apparently 

 by being stung. This does not kill it but renders it helpless, in which 

 condition it remains until destroyed by the larva of the wasp. 



The next act in this tragedy of nature is the finding of a suitable 

 place to leave the worm while a site for the home of the young wasp is 

 found. Always, so far as observed, the worm is left on some high place, 

 such as the top of a large clod of earth or in a fork of some plant an inch 

 or two above the ground. 



Dame wasp (for it is always the female that catches the cutworms) 

 does not believe in the old adage, "Never catch a bird until you have a 

 cage for it," as the worm is always secured before the burrow is dug. 

 The worm having been left in some place of prominence, the search for 

 a suitable location to dig a burrow begins. Mrs. Fossores (for this 

 is one of her names) does not consider "any old place" good enough 

 for a home for her young. One wasp was seen to start seven burrows 

 before finding a place entirely to her liking. The eighth location proved 

 satisfactory and the burrow was completed. Several of the unsatis- 

 factory attempts were made where the soil was soft and the digging easy; 

 however, an easy job did not seem to be what the wasp was looking for. 

 The location finally selected was in a hard beaten pathway where the 

 digging was very difficult. Thirty minutes were consumed in the con- 

 struction of the burrow. The wasp rested but once during this period 

 and then for but a very short time, when she lay flattened out on the 

 warm soil in the sunshine. 



( 4 - a ) See explanation of "Reference Figures," page 2. 



44 



