430 



Pemberton (C. E.). Insecticide Sprays : Their Relation to the 

 Control of Leafhoppers by Parasites. — Hawaiian Planters' Record, 

 Honolulu, xxii, no. 6, June 1920, pp. 293-295. 



In connection with spraying operations against the cane leaf- 

 hopper [Perkinsiella saccharicida] fears have been expressed as to the 

 result in view of the fact that some parasites are actually being des- 

 troyed and that Paranagrus optabilis is the chief agent in keeping the 

 leaf -hopper in check. A consideration of the life-cycle of the leaf -hopper 

 and its parasite and the comparative vulnerability of each to the spray 

 may however serve to allay these fears. 



During the winter and spring it was found that, on an average, it 

 required about 35 days for the leaf -hopper egg to hatch, 62 days for 

 the young insect to develop to an adult, and at least 15 days more before 

 the adult began laying eggs, this process continuing for at least 20 

 days. The parasite completes its development within the leaf-hopper 

 ■egg in about 42 days. As soon as it emerges it begins laying eggs in 

 those of its host, and has laid all its eggs and died in about 5 days. 

 Thus about 73 per cent, of the leaf -hopper's life is spent on the surface 

 of the sugar-cane, while only about 10 per cent, of that of the parasite 

 is passed under these exposed conditions. Consequently a much 

 greater proportion of all leaf-hoppers than parasites present will be 

 destroyed by spraying, and a change in balance is quickly effected. 

 Besides this the parasite begins ovipositing as soon as it hatches, 

 whereas the leaf-hopper does not begin to do so for about 77 days. 

 •Consequently many more of the parasites that are killed will have 

 laid a proportion of their eggs. A second spraying before 77 days have 

 elapsed is still more effective. It should be noted that the parasite 

 attacks even eggs that are ready to hatch, and develops successfully. 



In practice no detrimental effect of the spray on the parasite has 

 arisen, and the parasitism has increased from a very low point when 

 the spraying commenced to a much higher percentage in a short period. 

 Further a decided response in the growth of the cane has accompanied 

 this increase in parasitism and the decrease of a host of leaf -hoppers 

 through the action of sprays and hopper- catchers operated over the 

 entire area at the same time. 



FuLLAWAY (D. T.). The Fern Weevil Menace. — Hawaiian Planters' 

 Record, Honolulu, xxii, no. 6, June 1920, p. 299, 1 plate. 



The contents of this paper have already been noticed [R.A.E., A, 

 viii, 191]. 



Bridwell (J. C). U.S. Bur. Entom. Insects Injurious to the 

 Algaroba Feed Industry. — Haivaiian Planters' Record, Honolulu, 

 xxii, no. 6, June 1920, pp. 337-343. 



There are four insects effecting perceptible injury to the algaroba 

 IProsojns juliflora] crop. These are three beetles, which begin to infest 

 the beans in the field, viz. : — Bruchus -proso-pis (algaroba or mesquite 

 Bruchid), B. sallaei (glue bush Bruchid) and Pachymerus {Caryohorus) 

 gonagra (tamarind Bruchid), and a moth, Plodia interpunctella (Indian- 

 meal moth), which feeds in the pods during storage. Some of the 

 information given concerning these Bruchids has been already noticed 



