433 



mixtures were found to be useless, the lime itself doing severe damage 

 to the heart of the maize ; mixtures of arsenic and starch in propor- 

 tions of 1 to 30 or 1 to 40 were however effective. Mr. Ballou said 

 that Paris green and lime in the proportion of 1 to 6 should not render 

 the leaves repellent to the cotton worm and this was the proportion 

 used in most of the islands. With regard to the point that Montserrat 

 was infested with cotton worms from Antigua, Mr. Ballou said that the 

 powers of flight of the moth were extraordinarily great and it was 

 becoming the general opinion in America that the cotton worm did 

 not hibernate in the United States, but that every outbreak was the 

 result of fresh invasion. It is not certain that this moth does not 

 hibernate in some of the West Indian islands, and it is very hkely 

 that an island without a close season, hke Antigua, would enable 

 them to survive better than one like Montserrat, which has a close 

 season. 



Beelese (A.). Entomophagous Insects and their Practical Employment 

 in Agriculture. — Ivternat. Rev. Science & Practic. Agric. {Mthhj. 

 Bull. Agric. Tniell. Plant Dis.), Rome, vii, no. 3, March 1916, 

 pp. 321-332. [Eeceived 2nd August 1916.] 



^The action of natural entomophagous enemies of insect pests is not 

 ^always so clearly defined as in the case of Novius cardinalis and Icenja 

 pitrchasi. The increase of pests is subject to a number of factors, and 

 entomophagous enemies do not always play the most important part. 

 These enemies are divided into predatory species, which hunt and 

 devour other insects or their eggs, and endophagous species, which 

 develop in the body of the victim or in its eggs, or which devour the 

 €ggs within the mother. Both groups include monophagous insects, 

 Avhich only attack one species, and polyphagous insects, which attack 

 several species. As a general rule endophagous insects are more useful 

 than predatory ones, and polyphagous less so than monophagous. 

 The first section of this paper deals with entomophagous insects with 

 useful action in the absolute sense, i.e., against insect pests of agricul- 

 ture. The two most striking instances of this are provided by N. car- 

 dinalis against I. purchasi and by Prospcdtella berlesei against Aidacaspis 

 (Diaspis) pcMtagona [see this Revieiv, Ser. A, i, p. 189 ; ii, pp. 292, 403 ; 

 iii, pp. 5, 6, 251, 256, 524]. In both cases the beneficial species, 

 imported some time after the harmful one, has been free from its own 

 enemies, as found in its native country. Another, but less definite 

 instance, is furnished by the Chalcids imported into the Hawaiian 

 Islands to combat the Austrahan Fulgorid, Perkinsiella saccharicida, 

 very injurious to sugar-cane [see this Revieiv, Ser. A, iii, p. 758]. 



The second section of this paper deals w^th entomophagous insects 

 of mediocre efficacy and intermittent in action. Their useful action 

 is less sure, less constant and less uniform, either because they are 

 themselves attacked by other entomophagous species or by other 

 adverse factors, or because their victims are chiefly controlled by other 

 special factors. The following are examples of insects belonging to 

 this category:- — Scidellista cyanea against Saissetia (Lecanium) oleae, 

 Cryptolaemus montrouzieri against various scale-insects ; Orcus chaly- 

 'baeus and other Coccinellids against Aspidiotus perniciosm : and 

 Hippodamia convergens against Eriosoma {Schizoneura) lanigerum. 



