Packard.] INSECTS OF THE FIELD. 217 



tract of countr}'. Ploughing in the stubble in this case 

 does not injure the insects, as with their hard bodies they 

 can work their way out of the earth. The joint w'orm has 

 several parasites, members of its own family, and it must 

 be a pleasant sight to the agriculturist, however it may 

 strike the moralist, to see the members of this large family 

 falling upon and destroying one another, and in such an 

 atrocious way, too. Indeed, our sole dependence for protec- 

 tion against noxious insects is the literally intestinal wars 

 by which their numbers are kept down to a moderate figure. 



The Army worm of the north is essentially a field insect. 

 It is not usually a common object, but at long intervals it 

 swarms in immense numbers, cutting off acres of wheat, 

 barley, oats and grass. This worm is the caterpillar of the 

 Leucania unipuncta, one of the family of night-flying moths, 

 represented by the cut worms (Agrotis, see Figs. 9, 10, 11) 

 and Cucullia, etc. The present moth is rusty grayish ochre- 

 ous brown, with the wings free from the usual markings, and 

 only a few dark dots forming a row parallel to the outer 

 edge of the wing, with a single white dot near the centre of 

 the wing. She probably lays her eggs near the roots of 

 grasses, such as the timothy and red top, about the middle 

 of June. In the Middle and Western States the eggs arc 

 probably laid in April and May, and the moths lay their 

 eggs for a second brood in June and Jul}-, while in New 

 England the moth appears in October, and probably then 

 lays eggs which do not hatch till the spring. 



The caterpillars on hatching feed for al)out four weeks, 

 until nearly fully fed, when they stray oif to seek fresh pas- 

 tures. Usually their numbers are inconsiderable, but several 

 times during the last and the present century they have ap- 

 peared in immense armies. In New York and Now England 

 they have occurred in great numbers in 1743, 1770, 1790 

 and 1817. In southern Illinois they abounded in 1818 or 

 1820. In 1842 they were very destructive. In 1856 they 



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