( «i ) 



feed on it, one of which, the Brewer blackbird (Etiphagus 

 cyanocephalus) took 95 per cent, of all the butterflies eaten by 

 the bii'ds. The birds, in feeding on the butterfly were stated 

 to attack the insect at a critical point in its life-history, and 

 were therefore of more value as a check than they would have 

 been had they fed on the larva or pupa. The smaller birds 

 probably had a more intimate relation to the outbreak when 

 the insect was in the larval or pupal stage. The data col- 

 lected showed of what value birds may be in the checking of an 

 insect outbreak rather than their value in the prevention of 

 such an outbreak. 



Geometbid Moths op the genus Aletis, and their mimics 



FROM the neighbourhood OF ENTEBBE. Prof. PoULTON 



exhibited a large but not quite complete series of the members 

 of this important combination collected, between May 23, 

 1909 and September U, 1910, by Mr. C. A. Wiggins, 

 D.P.M.O. of the Uganda Protectorate. The specimens had 

 been collected just as they were met with, and in sufficient 

 numbers to give some indication of the proportions. By far 

 the most abundant species was Aletis (Leptaletis) erici, Kirby 

 (56 examples). A. helcita, Clerck, although much commoner in 

 collections, was comparatively a rare insect (4). The explanation 

 of its prominence in collections is probably to be found in the 

 fact that helcita is rather larger and of a richer colour than erici 

 and has been mistaken by collectors for fine specimens of the 

 common species. There are in the British Museum two rows 

 of helcita, but only three examples of erici. Another common 

 species of Aletis — paler and smaller than either of the above — 

 was Aletis {Leptaletis) forbesi, Druce (11). The following 

 mimics were also present, all of them in very small numbers : 

 the Hypsid moth Phaegorista similis, Walker (2), the female 

 Agaristid moth Xanthospilopteri/x poggei, Dewitz (1), the 

 Nymphaline butterfly Eujyhaedra ruspina, Westwood (2), the 

 Lycaenid butterfly Telipna ni/anza, Neave (1). The propor- 

 tions of the three species of Aletis seem to be about the same 

 in the Lagos district, where Mr. W. A. Lamborn has bred 

 erici and helcita, and finds that their caterpillars have different 

 patterns, and that erici is gregarious and helcita solitary in the 

 larval state, 



A 2 



