Imperial Valley press., 1910-07-02
TO KILL ALFALFA WORMS
Pests May Be Starved, Drowned or Dried Out, Say State Bug Experst
 In The Valley.

of the U. S. Department of Agricul- | ture and Mir. Walter E. Packard of the State Experiment Station, located at Fl Centro, regarding the destruc- tive alfalfa worm.
 "The damage done by the larvae of the yellow butterfly to the alfalfa has become so serious that it was thought best to give certain tentative results regarding the control of this pest, which have been reached so far in the investigations started this spring by both the State Experiment Sta tion and the IT. s. Dept of Agricul- ture. Since the investigations look ing toward the control of the butter fly have not yet gone over single season, absolutely conclusive results can not be given. The suggestions offered therefore, should be consid- cred only as a probable means of handling the problem.
 "The alfalfa butterfly (Colias eury- theme) is the cause of so much dam age in this section of the country, because the growing period of the alfalfa extends over such a great such a great length of time and be- cause the winter season is so mild. The butterfly hybernates in the pupal stage during the winter months and, at the beginning of spring, those that have survived the unfavorable condi- tions and the attacks of their natural enemies issue as butterflies and begin to lay a large number of minute oblong, whitish eggs on the leaves of the alfalfa. These soon hatch and later appear as the destructive green worms, which rest on the stems of the alfalfa and feed on the leaves. In due time they pass through the regular life history and emerge as butterflies. At the present time the third brood is doing the damage to the alfalfa.
 "It seems that large proportion of the worms can be killed by cutting the second crop earlier than is the common practice throughout the val ley; but since time for such action has passed, the best thing that can be done is to cut the present of future crops as soon as the worms appear in the fields, and thus not only save some of the crop affected but also prevent the majority of these worms from maturing and laying more eggs for the next brood. Many worms are shaken of in the wind-row or the hay cock during the process of making hay, but large per cent. of them die of starvation, as the new growth does not come on in time to give them sufficient nourishment. The degree of success obtained by these means will depend materially on thorough and clean cutting. The shorter the hay is cut and the less green alfalfa left on the borders, ditch banks and turning rows, the less op- portunity there will be for the worms to tide over this period By irrigating with big head of water immediately after removing the hay many of the worms remaining will be drowned. Of course care should be taken in this case not to scald out the alfalfa Exactly opposite to this method is one in which the field is allowed to go dry for week or so after cutting, thus insuring the starvation of all larvae present. A number of farmers have inaugurated the practice of al- lowing their fields to go dry during August, claiming that they thus se- cure better crcps the following fall. If all of the farmers of the valley would do this, the probabilities are that the crop of worms for next year would be reduced. Even if the farm CTS of a single locality should fol- low the suggestions given here, the serious conditions which now exist would be alleviated, but the com parative success depends upon the CO., operation of all of the alfalfa growers of the valley.
 "A certain parasite, natural to the valley, has been found in many of the fields attacking the worms, but so far has not been present in sufficient numbers to be of any great economi- cal importance. In dealing with any fields such as this. spraying or other similar methods of procedure are manifestly impossible"
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