INSECTS 1S1 



damage on crops. Among the former the two commonest and most mischievous 

 are members of the genus Acridium, one being known as the " redwing," and the 

 other as the brown locust. The redwing, which is the larger of the two, and nearly 

 related to the locust of North Africa and Syria (Acridium peregrinum), is 

 essentially an Eastern species, the migrations of which are in the main restricted 

 to the districts fringing the Indian Ocean. The brown locust, on the other hand, 

 is as distinctly a Western form, which prefers the dry and desert districts of the 

 interior. In some years, however, owing either to unusual migrations or to 

 prevalent winds, the distributional areas of the two species overlap to a greater or 

 less degree. This was markedly the case during the summer of 1907-8, when 

 Cape Colony, the Transvaal, and Rhodesia were visited by both kinds, while the 

 redwings invaded Natal, Swaziland, and Mozambique. As the two species breed 

 at different seasons of the year, it is essential to determine which has to be dealt 

 with at any particular time in any one district when measures for their extermina- 

 tion are undertaken. The brown locust lays its eggs much earlier than the red 

 species, and in consequence of this the campaign against the immature insects, or 

 " voetgangers," is practically completed before war is waged against those of the 

 red species. The eggs of the brown locust will not hatch till they have received 

 a sufficient supply of moisture, and failing this will remain dormant for a long- 

 period — it is said for as much as ten years, although a period of five years is the 

 utmost that has been verified. The eggs of the redwing, on the other hand, hatch 

 in about thirty days after they are laid. Most of the eggs of the brown species 

 are laid from June to August, but some not till September ; by the end of the last- 

 named month voetgangers from the earlier batches begin to make their appearance, 

 but the hatching process in the Transvaal is not finished till the following January. 

 When the redwing lays somewhat earlier than usual, voetgangers of both kinds 

 may be simultaneously on the move in certain parts of the country. 



A very remarkable locust, Methone anderssoni, which inhabits the desert 

 tracts of southern Africa, is the sole representative of its genus, and at the same 

 time one of the largest members of the family Acridiidce. With mere rudiments 

 of wings and very feeble of locomotion, it is a sedentary species which apparently 

 depends for protection chiefly upon its unrivalled vocal powers, which attain their 

 highest development in the males. It is suggested, indeed, that the latter have 

 the power of uttering two distinct kinds of notes : one, which is common to the 

 females, of an altogether peculiar type, and a second which is more or less similar 

 to that of locusts in general. 



Lake Tanganyika is the home of a small species of free-swimming 

 jelly-fish, or medusa, which has been made the type of a genus by 

 itself, under the name of Limnocnida. This genus appears to be nearly allied to 

 Limnocodium sowerbyi, first discovered in the Victoria regia tank at the Royal 

 Botanic Gardens, London, and probably a native of the Amazons ; a second species, 

 L. kaivaii, inhabiting the Yang-tsi-kiang. The Tanganyika species has also been 

 discovered in the Niger ; and a second generic type, Mcerisia, inhabits Lake 

 Karun (the ancient Moeris) in the Fayum district of Egypt. When Limnocnida- 

 was first discovered in Tanganyika it was regarded, like the above-mentioned 

 snails, as affording evidence of the recent connection of that lake with the ocean. 



