ANNUAL REPORT, 1943-44 29 



Spotted Fireworm {Cacoecia parallela (Rob.)). The bog in Marion mentioned 

 in last year's report^ was seriously attacked by this insect again this year, the 

 last of May. The worms were completely killed out b^' flooding for 30 hours on 

 June 5 and 6. The winter water had been remove4 from this bog on May 10. 



Cranberry Scale (A. oxycoccus Woglum). A rather severe infestation of this 

 species on a part of the large bog of the Nantucket Cranberry Company was 

 treated very successfully in the early spring, after the removal of the winter 

 flood, with the following sprays, each used at the rate of about 500 gallons an 

 acre^: (1) Dry lime-sulfur, 16 pounds in 100 gallons of water; (2) Pratts Spra 

 Cream, 1 gallon in 100 gallons of water. 



Nearly all the scales were killed by these spraj's. The lime-sulfur did almost 

 no harm to either the cranberry vines or their crop. The oil spray stunted the 

 berries somewhat and retarded the new vine growth rather noticeably. 



Grape Anomala (Anomala lucicola Fab.). Grubs of this species were sent to 

 the Japanese and Asiatic beetle laboratory at Moorestown, New Jersey, to have 

 their susceptibility to the milky disease organism determined. Mr. C. H. Hadley, 

 in charge of the laboratory, reported the following results. 



Further reference is made to earlier correspondence, particularly Dr. 

 Hawley's letter to you of January 18, regarding the susceptibility of 

 Anomala lucicola to type A milky disease. Our tests to determine the 

 susceptibility of this species to infection by type A milky disease have 

 now been completed, and you will be interested in the results. 



The grubs used in the test were those which you kindly sent us late in 

 November 1942. Of the surviving larvae of that shipment, 10 were 

 inoculated by direct injection with spores of the type A milky disease, 

 Bacillus popilliae. Five of these larvae developed typical t\pe A vege- 

 tative forms and spores. After 10 days incubation at 86°F. the infected 

 larvae differed but little in macroscopic appearance from the noninfected 

 specimens which had been injected, the typical chalky-white appearance, 

 characteristic of milky diseased Japanese beetle larvae, not being evident. 



Twenty of the healthy larvae were exposed to infection in soil in which 

 the concentration of type A milky disease spores was 2 billion spores per 

 kilogram of soil. These larvae were incubated at a temperature of 86°F., 

 examined at frequent intervals, and held until all the larvae had pupated 

 or died. After 25 days incubation, each was examined microscopically 

 for the presence of milky disease. In no case was there evidence of posi- 

 tive infection. 



These tests would seem to indicate that this species possesses a relatively 

 high degree of natural immunity to type A milky disease. Of course the 

 number of larvae employed in the test was rather limited, so that probably 

 it should not be said that this species is completely immune to field in- 

 fection from t>'pe A disease. However, in view of the fact that direct 

 injection of spores known to be viable produced only 50 percent infection 

 under incubation conditions known to be very nearly optimum 

 for the development of the disease, it may be assumed that this species 

 is certainly less susceptible to the disease than Japanese beetle larvae, 

 and is probably rather highly immune under ordinary field conditions. 



Specimens of the infected larvae which did react positively were for- 

 warded to the Division of Insect Identification of the Bureau and identi- 

 fied by Dr. Boving as Anomala lucicola. His identification confirms that 

 given by you in your letter of January 18, 1943. 



Incidentall}', Dr. Hawley's letter to you of January 8 is now known to be 

 incorrect in so far as the susceptibility of the larvae to feeding in infected 

 soil is concerned. At that time several of the larvae in the feeding test 

 were suspected of being infected w ith milky disease. Later, however, 

 when blood smears of the suspected larvae were examined microscopically 

 it was found that these larvae were not infected with milky disease. 



' Mass. Agr. Expt. Sta. Bui. 398:26. 1943. 



' Information from Marland Rounseville, the foreman. 



