A KEVISION OF THE GENUS LOCUSTA. L. 



159 



The extremely variable and decidedly protective general coloration of the solitary 

 phase of pardalina in all stages of post-embryonic development, noted by Mr. 

 Faure, exactly corresponds with the coloration of danica. The larvae of the swarming 

 phase of pardalina present an astonishing likeness to those of migratoria and migra- 

 toiroides, the coloration presenting the same combination of orange and black.* 

 The adults of the swarming form are rather uniformly coloured, and some bright 

 yellow specimens in the series sent from Pretoria lead me to the suggestion that 

 at the time of mating a general change of coloration may occur, as it does in migratoria 

 (see p. 143). In the coloration of the most aberrant individuals of the solitary 

 phase, one particular feature is noteworthy : the presence of a more or less pronounced 

 pale or white oblique cross on the pronotum, which design is very characteristic 

 of the species of the closely related genus Oedaleus. 



An examination of the male genitalia revealed no difference whatever between 

 the two phases of pardalina, but this was only to be anticipated. 



The above-quoted conclusions of Mr. J. C. Faure concerning the transformation 

 of the solitary phase into the swarming one, at which he arrived quite independently 

 of m-y work on migratoria, give a very strong support to the theory of phases as a 

 direct cause of the periodicity. His observations are especially interesting because 

 they concern the period of the transition from the solitary to the swarming phase, 

 on which my investigations of migratoria have given very few facts. It seems that in 



Fig. 6. Front view of head of : A, Locusta migratoria ph. danica, L. ; B, Locusfava pardalina 



ph. pardalina, Walk, (x 4). 



pardalina the transformation of solitary individuals into the swarming phase takes 

 more than one generation, but the actual causes of the transformation are in this 

 case also obscure, as they are in migratoria. Data as to the migrations of the flyers 

 and the fate of migrating swarms of pardalina are yet lacking, and further 

 investigations of this problem, closely connected with the careful study of all 

 conditions of breeding grounds, are extremely important from the point of view 

 of locust control in South Africa. 



V. Systematic Part. 



Key to the Genera Locusta, L., and Locustana, g. n. 



1 (2) Frontal ridge not widened at the median ocellus (fig. 6, A). Pronotum (fig. 1, 

 A, B, C, D, E) with the typical transverse furrow cutting the median keel 

 about its middle ; furrows in the prozona feeble. Mesosternal lobes only a 



* It is extremely interesting to note here that the larvae of most swarming and migratory locusts 

 {Schistocerca peregrina, Ol., Dociostaurus maroccanus, Thb., etc.) present the same general type 

 of coloration in black and reddish, or j'ellow, forming a very striking design. This phenomenon 

 is well worth further investigation. 



