December, '10] TITUS: alfalfa leaf- weevil 461 



Spring Feeding Habits 



They appear again at the first approach of spring and begin feeding 

 on the alfalfa, making punctures in the stalks. This is very different 

 from the summer and fall feeding when they rasp the epidermis from 

 the stalk and slit the leaves into ribbons. 



The feeding-puncture is irregularly oval in outline and usually made 

 by slitting and gnawing the cavity. The weevil apparently gouges 

 out its food and will stand for some time working small pieces loose; 

 it will then withdraw the beak, chew and swallow the food and again 

 return to the puncture. The injury is very often severe, especially 

 to young stalks which are so deeply cut that many wilt and break off. 

 During the warmer part of these earlj' spring daj's weevils have been 

 noticed mating, and egg-laying certainly commences soon after they 

 come from hibernation. The spring flight begins with the first con- 

 tinued warm weather. 



OVIPOSITION 



The eggs are at first laid singly on the plant; in the buds, axils o^ 

 the leaves, on the stalk or beneath the leaf sheath. In this latter case 

 the ovipositor is inserted thru the sheath, the egg being placed inside 

 in contact with the stalk and not in the tissue of the leaf as reported 

 for P. nigrirostris by Wildermuth.^ Two to three weeks after egg- 

 laying commences the female begins ovipositing in the stalks and this 

 form of oviposition becomes more common as the season advances. 



The egg-punctures are usually clean-cut and almost circular in out- 

 line. The weevils seen making these punctures made but one cut 

 with the beak. Standing lengthwise of the stem, head downward, the 

 beak was inserted at an angle slightly toward the base of the stalk and 

 given a steady pull up and in, thus making an elongated slit inside the 

 stem, both below and above the puncture. The beak was then wdth- 

 drawn and the insect either turned around or walked forward and 

 pushed her ovipositor into the puncture. From thirty seconds to two 

 minutes were occupied in laying the egg, the ovipositor being with- 

 drawn after each egg-deposit. 



Sometimes a puncture is filled with eggs until they project from the 

 aperture. When the female does not fill the puncture with eggs she 

 sometimes plugs it with a small ball of excreta or a little mass of epi- 

 dermis gnawed from the stalk. Sometimes before inserting the beak 

 to make the puncture she first gnaws away the epidermis. 



Egg-punctures in a slender stalk may cause the leaves to wilt and 

 the stalk to die and the same thing occurs when too many egg- 

 punctures are made in a larger stalk. 



'1909: Webster: U. S. D. A. Bur. Ent. Bui. 85, pt. 1, p. 9. 



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