476 MRS. O. A. MEKRITT HAWKES ON THE 



are many easily procurable varieties, which, as far as is known, 

 ai-e not regional. 



Palmer (21) worked for some time at Adalia, but she had only 

 a few varieties to deal with, as in America there occurs only the 

 " type" and three varieties, whilst in Europe there a,re more than 

 twenty-six named varieties. It would be impossible to get as 

 quick results here as in America, as two generations per annum 

 are the most one can obtain in England luuler natural conditions, 

 whereas Palmer succeeded in obtaining four and five during the 

 long American summer. Our erratic climate also makes the 

 food-supply (aphides) more uncertain than under more stable 

 climatic conditions. 



Coccinellids have been extensively studied in the United States, 

 as they are there recognised to be of considerable economic 

 importance ; but in England there has been little careful study 

 of their haljits, their distribution, or the genetical and possibly 

 regional relations of the varieties which are so numerous in some 

 of the species. Donisthorpe (6) has published the only complete 

 history of any species, Coccinella cUstincta. The following obser- 

 vations were made in the course of genetical experiments which 

 are still in progress. 



The varieties of Adalia have been determined chiefly by 

 Meissner and Schroder, who based their determination principally 

 upon the variations in the colour of the elytra, but neglected the 

 very considerable variations of the thorax. Schroder believes 

 that the varieties from pure red elytra at tlie one extreme to pure 

 black at the other are modifications of a scheme of seven spots 

 and a scutellar mark. This is an interesting matter of specu- 

 lation, but we do know that in Europe there are two piincipal 

 forms: (1) "type," in which the elytra are a reddish brown 

 with an approximately round black spot in the middle of each 

 elytron ; and (2) a black form with eithei' two or three red spots 

 in each elytron : when two are present, an upper lateral and a 

 mid-dorsal, the variety is known as var. A-mactdata ; when three 

 are present, an anal red spot being added to the above two, the 

 variety is named 6-pitstidata. All other varieties, none of which 

 occur in large numbers, can probably be grouped about these two 

 main forms. 



The Red varieties are generally acknowledged to be commoner 

 than the Black, though very few accurate statistics have been 

 i-ecorded. Meissner found 35-2 per cent. Black in Summerfeld 

 and 42-3 in Potsdam. In Staffordshire and Warwickshire I 

 found 29 per cent. Black in 1918, 25 per cent, in 1919. In 1920 

 I found 2-75 per cent. Black at Crouch Hill, London, N., 42*7 per 

 cent. Black on hops at Bishop's Frome, Herefordshire, 11*7 per 

 cent, at Enville, Staffordshire, and, very much to my surprise, 

 78-5 per cent. Black in the Edgbaston district of Birmingham. 

 Further observations will show whether localities are charactei-ised 

 by certain varieties or whether the prevalent vai-ieties vary from 

 time to time. If the varieties remain tlie same, will it mean that 



