LIFE HISTORY AND CONTROL OF HOP FLEA-BEETLE. 41 
SECOND CLASS.% 
Rhubarb (Rheum officinale Baill.). Tomato (Lycopersicum esculentum 
Potato (Solanum tuberosum L.). Mill.). 
Pigweed (Amaranthus retroflerus L.). Potato (Solanum tuberosum L.). 
Dock (Rumex obtusifolius L.). Pigweed (Amaranthus retroflerus L.). 
Sorrel (Rwmex acetocella L.). Red clover (Trifolium pratense L.). 
Red clover (Trifolium pratense 1L.). Dock (Rumex obtusifolius L.). 
Sorrel (Rumex acetocella L.). 
- Finding that the beetles did not care for certain plants after they 
had fed upon hop or mangel, an attempt was made to starve them 
to the food which was apparently most disliked. A large number of 
beetles were accordingly confined with red and white clover and with 
sorrel. Although the blossoms of the white clover were slightly 
attacked, the beetles finally starved to death on these plants. 
Portions of plants attacked.—During the spring and early summer 
the beetles fed upon the shoots and tender buds and ate holes the size 
of a pin head in the leaves. (See Plate III.) In cases where the 
leaves were very thick the lower surface tissues were left. These, 
however, soon dried and fell out, leaving a clean hole which, as the 
leaf expanded, became larger, sometimes reaching one-fourth of an 
inch in diameter. In feeding upon the hop plants, the beetles dug 
small pits in the shoots, which when the attack was severe caused the 
death of the stem. In the fall the beetles climb the trellis poles and 
crawl along the vines until they reach the hop cones, of which they 
are very fond. 
Destructive power by feeding.—When the beetles appear in large 
numbers they will devour a plant completely. In the spring of 1908 
they kept the yards bare until the last of June or the first of July, and 
when the mangels were coming up the beetles damaged them so 
severely that one planter found it necessary to sow three times in 
order to get a stand. In the fall, after the hopyards were cleaned up, 
the beetles migrated to the nettles along the fences and completely 
devoured them. The beetles were at this time in exceptionally large 
numbers; under ordinary conditions their attack is not so severe. 
Activity and migrations.—The flea-beetles that have just emerged 
are soft and sluggish and are readily picked off of the vines with the 
fingers. Within a few days, however, they become very active and it 
is then almost impossible to catch them in the hand. During the 
spring and summer of 1909 the beetles migrated little, if at all. The 
infested regions did not enlarge or change from the time that the 
beetles appeared in the spring until they disappeared in July. The 
@Plants of the second class are eaten very slightly, unless the beetles are 
starved to them. 
