HOP-INSECTS. The most destructive in sect enemy of the hop crop is the bop-aphis. Other species are of less importance, but they sometimes do considerable damage to the plant. The hop-grub or hop-plant borer (Gortyna manis) is the larva of a noctuid moth which lays its eggs in the early part of the season upon the young shoots of the plant. The young cater pillars. which are slender and greenish in color spotted with black, bore into the vine just below the tip and remain at this point for some time. The head turns downward and stops growing. Such vines are called 'muffled beads' or 'stag vines,' and sometimes 'bullheads,' the cater pillar at this time being called 'tip-worm.' A little later it drops to the ground and enters the stem at the surface of the ground. It is then called the 'collar-worm,' changing to a white color with black spots. About the end of .July it becomes full-grown and transforms to pupa near the roots of the plant. The moth issues in the fall or in the spring.
A number of different caterpillars feed upon the foliage. The hop-vine snout-moth (Hypena humuli) is one of the principal forms. The
larva of two butterflies (Pulyyonia interroga tionis and Polygonia comma) feed quite abun dantly upon this plant and are known to hop growers as 'hop-merehants' from the gold and silver markings upon the ehrysalids. The zebra caterpillar (larva of llamestra pieta). the com mon woolly-bear caterpillar (larva of Spilosoma riryinica), and the saddle-back caterpillar (larva of Emnrctia stimulca) are the renmining prin cipal species. One of the leaf-hoppers, TO ti gonia confluenta, causes more or less damage to the foliage, and the striped tlea-beetle (Phyllo treta villain) also damages the leaves, while the so-called 'red spider' or 'spinning mite' (TI trona ehus telarius) often causes the leaves to turn yellow. The best remedy for all of thee insects consists in spraying at the proper time. using an arsenical spray for the caterpillars and the flea-beetle, a kerosene emulsion for the leaf hoppers. and a sulphur wash for the spinning mite. Consult Howard, "Pests of the Hop Crop," in The Hop Industry (New York, 1898).