Plant Diseases and Insects. 1 1 1 



and his carr3'ing this micrococcus in cultures over winter are 

 promising facts, as is also Professor Osborn's contaminating 

 cabbage worms in Iowa with specimens brought from Illinois. 

 Congress, having at its last session appropriated ^2,500 for 

 some further investigation of the boll worm, the possibilities 

 in this direction for this particular insect have caused me to 

 plan investigations having for their object thorough field ex- 

 periment with some of these disease germs. 



^' Heliothis arniigera, the boll worm, is one of those cosmo- 

 politan insects which has become more injurious in the United 

 States than in any other part of the w^orld, by virtue of its 

 partiality for green corn, green cotton bolls, and green toma- 

 toes. The polyphagous and partially endophytous habit of 

 the larva renders its destruction difficult, except during the 

 earlier free-living stages by the fine spraying of the arsenites 

 on the under surface of the leaves. The ideal treatment for 

 the larger burrowing worms is some rapidly spreading dis- 

 ease germ that would penetrate and destroy them in their 

 hidden recesses. The insect was reported as extremely 

 abundant in cotton bolls during the summer, especially in 

 Texas ; but by the time the appropriation became available 

 its numbers had decreased, and it was too late in the season 

 to do much more than prepare for next year. We may expect, 

 as a result of special investigation, much additional fact and 

 experience both as to habits, natural enemies and means of 

 control ; but it is my desire to make the trial of these disease 

 germs the special feature of the investigation. Of those em- 

 ployed in the investigation, F. W. Mally was a former assis- 

 tant to Professor Forbes and has some experience in the study 

 and culture of disease germs ; while Dr. A. R. Booth is some- 

 thing of an enthusiast on the subject and has already estab- 

 lished the suceptibility, through contact, of the boll worm to 

 the cabbage worm micrococcus (J/, pieridis) of Burrill. We 

 hope to carry the germs through the winter so as to continue 

 the experiment as early as possible next year. I have in 

 mind as probably the most promising germ, that which affecfts 

 Nephelodes violans in a similar epidemic way, but which, as 

 Professor Forbes informs me, is a quite distinct micrococcus, 

 and I shall be pleased to have any of you co-operate with me 

 next year, by informing me of any disease of this character 

 that may prevail in your several localities." 



