202 A. D. PEACOCK— ENTOMOLOGICAL PESTS 



affected first, the older and larger leaves afterwards, and the petioles and stalks 

 become distorted till the whole plant presents a most forlorn appearance. The 

 native variety among the Agege cotton was also similarly affected. 



The disease was first observed in the Ishan Cotton, by the Assistant Super- 

 intendent of Agriculture about 20th July 1912, the cotton being then a month 

 old and 9 inches high. No insect or mite was discovered, and the cause of the 

 trouble is probably physical. 



From the end of August to the end of October 1912 the trouble grew roughly 

 from about 8 per cent, plants affected to about 25 per cent. The percentage was 

 arrived at by observing, at different periods, the same plants to the number of 

 1,000 in the Ishan, and 1,800 in the Meko. 



The plants were spoilt for bearing, but how seriously cannot be stated here, as 

 further work was prevented owing to departure on leave. The matter was also 

 investigated by the Government Mycologist, who has reported on the subject. 



Beneficial Insects. 

 Ladybird Beetles. 



The two species obtained have only been observed at Ibadan, but as they are 

 quite common and widespread throughout Africa, it seems quite permissible to 

 say that they may be found all over the Colony. The adults and larvae have 

 very similar habits. The former appear early in August on the cotton plants, 

 climbing actively, and specially frequenting the haunts of the Aphid s, upon 

 which they live. 



Chilomenes lunata, F. 



These beetles may be observed pairing on the plants early in August, and 

 eggs were laid, in one instance, half an hour after pairing. 



The latter are yellow in colour, about 1 mm. in length, spindle-shaped, with 

 rounded ends. They stand on end and are found in clusters of six and more, 

 usually placed on the cotton leaves among green fly. The numbers noted in 

 various clusters were 6, 6, 7, 15, 18, and 21, an average of 12. In captivity the 

 eggs have been devoured by either the male or female or both, but only when 

 the usual food, green fly, has been absent. The eggs gradually turn a silvery 

 grey in colour and usually all hatch in about four days. 



The larvae are spiny and have a few large yellow spots. They are very active, 

 and very soon after hatching crawl over the leaves seeking their food. The 

 period of activity lasts 12-16 days. Three moults have been observed, at times 

 when the insects were about J, \ and f inch long. At the conclusion of this 

 period of activity the larva fixes itself to the leaf by its tail and the body 

 becomes rigid in a curved attitude. After a time the skin splits dorsally and 

 reveals a yellow pupa. 



The pupal period was found to be short, about 4-5 days ; but in one excep- 

 tional case it lasted for 10 days. The soft yellow pupae are about the size of 

 the adult ladybird. They are found, usually isolated, on the underside of the 

 leaves of the cotton plants. 



Whether the beetles feed solely on one species of green fly or on a number is 

 not known, neither are the indigenous plants which they frequent when cotton is 

 not growing. 



