480 



MRS. O. A. MEKHITT HAWKES ON THE 



burying itself in the process. Tiie head, the thorax, antl the 

 tough dorsal skin are frequently left untouched. 



There is, however, no special mode of attacking the aphis, and 

 certainly no painless method of dining. The hijmnctata catches 

 hold of a passing aphis and at once proceeds to devour it in spite 

 of its struggles, which continue far into the meal. The legs, the 

 wings, the head, and part of the cuticle of abdomen and thorax 

 are usually left. The meal may take as long as five minutes. 



The mother hipunctata is not very wise in her choice of a posi- 

 tion for her eggs — many are laid on leaves, but also many on the 

 branches and trunks of trees. I have even found them on wooden 

 palings and on stones by the side of garden-paths. As the young 

 larvae cannot wander far in search of food, and as the parent is 

 lacking in the instinct to lay eggs where there would be an 

 adequate larder, the capacit}^ for eating eggs and one another may 

 be of considerable biological value. Indeed, knowing what we 

 do of aphis, one realises that it would indeed be a wise Lady-bird 

 that could guarantee aphis for its newly-hatched young. The 

 period of incubation varies from three to nine days, and in that 

 time the aphis might have disappeared. In May 1918 the 

 damson-trees were covered with aphis for three weeks ; without 

 any apparent change in the weather, the aphis began suddenly to 

 descend the tree-trunks in myriads, and at the end of two clays 

 hardly an aphis could be found. I have found eggs laid on the 

 petals of a rose, but the petals fell before the eggs hatched. 



The use of cannibalism was well demonstrated in July 1920. 

 An isolated gooseberry -bush had every shoot attacked by aphis, 

 upon which large numbers of hipunctata larvae were feeding. At 

 the time when the larvae were beginning to pupate, a few cold 

 rainy days caused the aphis to completely disappear. At once 

 the larvfe began to attack each other and the pupae, and, finally, 

 themselves pupated on an entirely cannibal diet. I saw no signs 

 of migration from this bush on account of shortage of aphis. 



Cannibalism is probably of use in preserving the race during 

 periods of aphis famine, as the larvse, unlike the adults, cannot 

 live long without food. Cannibalism is not of the same biological 

 use to the imago, as its power of flight gives it a large range, 

 and, when necessary, it can remain long periods without food. 

 I have starved Lady-birds for three weeks, and at the end some 

 of the males were capable of successful fertilization. 



3. Notes on the Life- History. 



a. Mating. 



Mating takes place in captivity in the presence of plenty of 

 light, especially direct sunlight. The response to light is very 

 rapid. Immediately a box containing a number of Ladj^-birds is 

 put in the sunlight, they begin to move quickly, fly, and mate. 

 The same activity does not take place if the box is warmed with- 

 out light. Fresh air, especially moving air, is also conducive to 

 mating. 



A. hipunctata i^hoih polyandrous and polygamous. When a 



