12 



"worming," as it is called. Most conservative tobacco planters send their hands 

 through the fields to pick off the caterpillars and crush them, and rely upon no 

 other remedial work. 



Should the hornworrn prove too numerous and the practice of hand 

 picking too expensive, the plants must be sprayed with an arsenical 

 poison, either Paris green or arsenate of lead. The application of 

 Paris green has already been fully discussed. From experiments con- 

 ducted by Professor Gar man in Kentucky, it appears that the young 

 worms are more susceptible to the poison than the more fully matured 

 ones. The plants should be watched for the appearance of the young- 

 worms, and if spra} T ing is to be done at all, it should be done at this 

 time. A mixture at the rate of 1 pound of Paris green to 125 to 160 

 gallons of water has been found sufficient if the worms are not over 

 half grown in size. During the eight or ten days preceding harvest- 

 ing the crop, the tobacco plants should not be sprayed. This pre- 

 caution will insure practically none of the poison remaining on the 

 leaves. 



Concerning the use of arsenate of lead against the hornworrn, Mr. 

 Quaintance says: 



Its advantages over Paris green are that it is insoluble in water, and hence can be 

 used of any desired strength without burning or spotting the foliage; it is quite adhe- 

 sive and will remain on the foliage longer, thus obviating the more frequent spray- 

 ings or dustings necessary with Paris green; it is white in color, and hence is visible 

 on the foliage, and thus lessens the danger from poisoning. 



Directions for preparing arsenate of lead are given on page 14 of 

 Bulletin No. 3 of this station, which will be mailed to any person in 

 the Territory on request. Arsenate of lead, already prepared for use, 

 is now on the market, both as a dry powder and in paste form. One 

 such preparation, in paste form, is for sale in Honolulu. 



Quaintance mentions another method of interest in combating the 

 hornworrn. He writes: 



It remains to speak of another means that is much used in this State (Florida) to 

 lessen the number of hornworms. The fight is waged, however, against the adults 

 by using flowers of jimson weed (Datura stramonium ) and sweetened water poisoned 

 with cobalt. Late in the evening a quantity of the bloom of the jimson weed is pro- 

 cured and is placed promiscuously through the patch, in holes in horizontal slats, 

 supported by sticks or otherwise, and into the flower is placed by means of a quill a 

 small quantity of this poisoned mixture. This poison should be of about the follow- 

 ing proportions: Cobalt, 1 ounce; molasses or honey, one-fourth of a pint; water, 

 1 pint. The adults in their search for nectar frequent these flowers, and are thus 

 poisoned by this mixture, which they feed upon greedily. 



Doctor Howard, under the subject of remedies for the hornworrn, 

 emphasizes the necessity of removing all worms from the plants after 

 or during cutting for the reason that if this is not done the worms 

 will continue feeding on the leaves in the barn. 



