LIFE-HISTORY OF THE LADY-BIRD BEETLE. 



487 



and Red differing thus in degree of pigmentation. But those 

 Red forms, in which the black spot even stretches as a liand across 

 the elytra, do not necessarily have a more pigmented pronotum 

 than in " type." If an increase in the size of the black spot of 

 " type" means a step forward in a melanistic direction, one would 

 expect this tendency also to affect the pronotum. 



C. variabilis. 



C, variahilis has two forms of imagines, whicli in general 

 colour arrangement are similar to the two principal forms of 

 A. hiimnctata. I'here is a Black form with ten red-ochreous 

 spots and a Red (ochreous) form with fourteen black spots. The 

 difference in the shade of the red between the two forms is 

 much more marked than in Adalia. The red spots on the Black 

 frequently tend to carmine at the edges, but the red ground- 

 colour of the Red form would more accui-ately be described as 

 ochreous; it is never as deep a red as occurs in A. hipunctata 

 (type). I have no information of the percentages in which these 

 types occur. The Black form of variahilis is the " type,"' but 

 whether this indicates that it is the more common is unknown. 



The dimorphism in hvpanctata and variahilis is not equivalent 

 to that of Lina (18), in which there is a spotted and a melanic 

 form, for in that species there is certainly only one colour-pattern, 

 as the spots can be sometimes seen in the melanic form by 

 holding the wings up to the light. MacCracken (18) found the 

 melanism recessive. 



Two matings of rar/rt^iYis were made : (1) mating 17, J Black 

 X 2 Red produced 4 Red imagines; and (2) mating 18, cT Red 

 X § Black produced 4 Black and two Reds, As in hipujuctata, 

 there is no sign of dominance. 



A third mating (10) was made between a Red hipunctata 

 and a 5 Black variahilis, the result of which was 7 Red variahilis 

 and 5 Black variahilis. The two mated at intervals from 

 May 29 to June 26, and during that period laid eggs as follows : — 

 15 on June 3, 16 on June 4, 24 on June 12, 6 on June 18, and 

 15 on June 26 ; a total of 76. As the results were all variahilis, 

 one cannot but suppose that the female was satisfactorily ferti- 

 lised by a male of her own species before she was cauglit. This, 

 however, involves the necessity that some of the spermatozoa 

 remained capable of fertilization for 29 days at least ; but Palmer 

 states, p. 235 (21) : "A female Adalia would not seem to be able 

 to lay fertile eggs for more than three weeks after being isolated 

 from a male." 



On one point these two species differ considerably, for it is the 

 Black form of hipunctata which is tlie more variable in the 

 number of spots, whilst in rariahilis it is the Red foruj which 

 is the more variable. The recurrence of the same type of 

 variation in species so nearly related and which constantly occur 

 together, makes an understanding of the one imperative to a 

 satisfactory understanding of the other. 



