THE HAWAIIAN BEET WEBWOEM. 



Temperatures at Honolulu during the tune the species was reared. 



Month. 



1910. 

 Jul J' 



August 



September 

 October... 

 November 

 December. 



1911. 

 January. . . 



Minimum 



Maximum 



tempera- 



tempera- 



ture. 



ture. 



°F. 



Average 

 mean tem- 

 perature 

 for entire 



month. 





°F. 



69 



84 



60 



85 



69 



85 



65 



84 



66 



84 



62 



80 



58 



79 



°F. 

 76.5 

 76.8 

 77.0 

 75.3 

 74.6 

 71.2 



70.0 



NATURAL ENEMIES. 



At various dates larvae were collected in the field and confined in 

 cages in the insect ary. In this way three species of hymenopterous 

 parasites were obtained. These were Limnerium hawaiiense Cram., 

 Chelonus blacl-burni Cram., and Cremastus hymenice Vier. 



L. hawaiiense was obtained in greatest numbers during August and 

 September, while C. blaekburni apparently became more abundant 

 during December. C. hymenia was reared only in small numbers 

 and at all times appeared to be more rare than the other species. Xo 

 predaceous enemies were actually observed feeding on the Hymenia 

 larvae or pupa?, but on several occasions a species of wasp (Polistes 

 hebrceus Fab.) was seen buzzing about infested plants. During the 

 warmer months this wasp and allied species are efficient enemies of 

 the common cabbage worm (Pontia rajiw la.)', and it is not improb- 

 able that they also occasionally kill Ilymenia larvae. On the whole, 

 the natural enemies apparently do not reduce the number of Hymenia 

 larvae sufficiently to be of much practical value. 



EXPERIMENTS WITH INSECTICIDES. 



During the fall of 1910, an opportunity was taken to make some 

 experiments against the Hymenia larvae with insecticides. The ex- 

 periments were as follows: 



Experiment No. 1. — Paris green, 4 pounds, and lime, 4 pounds, in 

 100 gallons of water. September 1, three beds of table beets, each 

 10 yards in length and 1 yard wide, were sprayed with about 2 gal- 

 lons of this mixture. The application was made with a portable, 

 compressed-air sprayer, which was fitted with a short extension r rod 

 elbow and a Vermorel type nozzle. The mixture was applied chiefly 

 to the upper surface of the leaves and it adhered very well. The 

 weather at the time of the application was hot and clear and without 

 a breeze. 



The following day all the larvae were alive, except those on ac- 

 casional leaves which were poisoned on the underside. Thirty-three 



