. Bulletin. se is commonly known as thesmartweed-borer (P. obnmbratilis), which is found very commonly insmartweed throughout the entire state. The life history of this insectis approximately the same as that of the European corn-borer, therebeing two generations, the moths appearing in May and again the latterpart of July, and the insect passing the winter as a full-grown larva inthe stems of its food plants. Until the last two or three years, this in-sect was not generally known to infest corn, but investigations madeduring the past year have shown that it frequently winters in the cornplant
. Bulletin. se is commonly known as thesmartweed-borer (P. obnmbratilis), which is found very commonly insmartweed throughout the entire state. The life history of this insectis approximately the same as that of the European corn-borer, therebeing two generations, the moths appearing in May and again the latterpart of July, and the insect passing the winter as a full-grown larva inthe stems of its food plants. Until the last two or three years, this in-sect was not generally known to infest corn, but investigations madeduring the past year have shown that it frequently winters in the cornplant. A single specimen was found in grSen corn growing in a verylarge patch of smartweed about July 1, 1919. This specimen, however,had evidently gone to the corn from a newly mown patch of smartweeds. 892 and simply made a small hole near the base of the corn-stalk in which topupate. Early in the fall of 1919 examinations carried on throughoutthe state showed that this borer commonly leaves the smartweed early. I r n\ le of the smartweed borerU-!/iaut,(u obvmbratilis Lederer) instems of Amaranthus (left) and corn(right). in fall, where the infestation is heavy, and migrates to corn (Fig. 5) anda number of other plants. We have never taken it in corn where thecorn was growing more than thirty feet from infested smartweed. Itapparently does no injury whatever to the corn, simply boring a smallgallery in the stalk in which to pass the winter, and it does not enter 393 the corn plant until the ear is fully matured—in fact, generally not untilthe stalk is quite dry. Up to the present time this borer has been foundin the fall in the stems of the following plants: Smartweed Polygonum hydropiper L. Ragweed Ambrosia artemisiifolia L. •Giant ragweed A. trifida L. Indian mallow Abutilon theophrasti Medic. Jimson-weed Datura stramonium L. Goldenrod SoUdago sp. ? Lambs-quarters Chenopodium album L. Barnyard grass Echinochloa crus-galli Beauv. Foxtail grass Setaria glauca Beauv. Cocklebur
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Keywords: ., booka, bookcentury1900, bookdecade1910, booksubjectnaturalhistory
