200 A. D. PEACOCK — ENTOMOLOGICAL PESTS 



Green Fly. 



The specimens collected were identified by Mr. F. V. Theobald as Aphis 

 gossypii, Glov. The species is common at Ibadan, but nothing is known as to its 

 occurrence in other districts, nor as to the indigenous food-plants, if any. The 

 life-history has not yet been worked out. 



The numbers of this Aphis are fortunately kept well in check by natural 

 enemies. These include at least two species of ladybird, the larvae of three 

 species of hover flies, and the larvae of two species of lacewing flies. 



As an indication of the activity of the beneficial insects, two examples from 

 the field may be taken. A small cotton plant Avith six leaves, badly affected 

 by aphids, was being busily worked by 9 ladybird larvae and 3 hover fly larvae. 

 To provide for the future a set of a dozen ladybird eggs were also present. A 

 second similar plant had 3 ladybird larvae and 5 hover fly larvae. In the 

 laboratory, the usual allowance per day for two adult lady-birds was a leaf with 

 about 200 green fly upon it. The amount of useful work done by these checks 

 is incalculable. 



During the 1912 season the American cottons were most subject to attack by 

 aphis. At Ibadan the pests were plentiful enough, but they were so well kept in 

 check by enemies, that artificial methods of control were never warranted. This, 

 however, does not mean that watchfulness should be abated. Should the aphis 

 show the least sign of increasing beyond natural control, spraying must be done. 

 For this a resin wash is recommended. (See Lefroy's " Insecticides.") 



Leaf-eating* Beetles. 



The following beetles have also been observed to feed upon the leaves of 

 cotton plants : — 



Coccinellidae : JEpilachna chrgsomelina, F., E. similis, Mills., var. 



assimilis, Muls. (larvae found also on grass). 

 Lacriidae : Lagria oillosa, F., and L. viridipennis, F. (both species were 



also found on yam and cowpea). 

 Curculionidae : Siderodactylus sp. 



Chrysomelidae : Syagrus calcaratus, F. (Plate XXIV, fig. 6), Plagiodera 



circumduct a, Sahib., Ootheca mutabilis, Sahib. (Plate XXIV, fig. 8), 



Nisotra uniforma, Jac. 



The two species of Lagria were found to be widely distributed in Southern 



Nigeria, but the remaining species were noted only at Ibadan, where they all 



occurred commonly. 



While none of these beetles has been known to threaten the cotton crop 

 seriously, it is important to regard each species as a potential pest. Further, the 

 simultaneous activity of all the species may do quite as much harm as the 

 excessive preponderance of one. Young cotton, particularly, should be carefully 

 watched. Should the circumstances warrant, spraying with lead chromate is 

 recommended. 



Leaf-eating Caterpillars. 



Euproctis sp. 



Two specimens of this moth were found in the entomological collection upon 

 the writer's arrival, but owing to their poor condition they could not be 

 specifically determined. 



