270 



INSECTS INJURIOUS TO STAPLE CROPS. 



yellowish -green eggs uj^on the tips of the hop-vines just 

 as they begin to climb. ' ' The Qgg hatches in a few days 

 and produces a minute slender greenish larva, spotted with 

 black, which immediately burrows into the vine just below 

 the tip, and spends a part of its life in the vine at this 

 point. The vine soon shows the effects of the insects' 



Fig. 154.— Hop-plant Borer {Hydrceda immanis Grt.). a, enlarged 

 segment of larva; h, larva; c, pupa; d, adult, natural size. 

 (After Howard, U. S. Dept. Agr.) 



work; instead of pointing upward, embracing the pole 

 readily and growing rapidly, the tip points downward, will 

 not climb, and almost entirely ceases growing. This 

 appearance is called by growers a "^ Muffle-head.' When 

 the insect attains a length of about half an inch, or 

 slightly less, it leaves the tip, drops to the ground, and 

 entering the stem at the surface of the vine, feeds upward, 

 interrupting the growth of tlie vine and lessening its 

 vitality; the larva now changes color, and becomes a dirty- 

 white, with a strong, deep reddish tint, with numerous 

 black spots. The larva, now about an inch in length, and 



