June, '11] quayle: scale insect locomotion 301 



still feeding and without signs of pupation. During the winter and 

 spring of 1908, the writer was engaged on other work, and compelled 

 to neglect the notes on this borer. However, on July 9, the cage was 

 again examined, and a single female beetle found beneath the pole. 

 July 27 a male was taken from the cage, and another of the same sex^ 

 two days later. On August 17, another female was secured. No 

 more adults appearing, the pole was later taken out, and split up, no 

 larvae or pupae being found. 



While incomplete, these records show that the life cycle of this 

 beetle extends over a period of at least two years, and more likely 

 three years are occupied in its various transformations. 



LOCOMOTION OF CERTAIN YOUNG SCALE INSECTS 



By H. J. Quayle 



The object of this paper is to present a few experiments on the 

 powers of locomotion of the Black Scale (Saissetia olece Bern.), the 

 Red or Orange Scale {Chrysomphalus aurantii Mask.) and the Purple 

 Scale {Lepidosaphes heckii Newm.). These three scales represent 

 the most important insect enemies of citrus trees in southern Cali- 

 fornia, and the question of how they are spread and what part their 

 own powers of locomotion play in the matter frequently come up for 

 discussion. 



The distribution of scale insects over long distances is effected 

 mainly through the interchange of nursery stock, and over the same 

 general community by birds and active insects, chiefly, together 

 with the agency of man in his usual cultural operations, while in the 

 spread from tree to tree or to nearby trees, aside from the above 

 factors, the power of the insects to transport themselves must be 

 taken into consideration. The wind is another factor which may aid 

 certain insects in distributing themselves, either by blowing them 

 directly or with a leaf or light twig upon which they may be resting. 

 Such insects as winged plant lice or the males of scale insects have 

 frequently been observed to be wafted by a gentle breeze or aided in 

 their flight through its influence. Experiments with a foot bellows 

 showed that young black scales are not very readily dislodged from 

 a tw4g, but once dislodged might be carried a short distance as they 

 fell. Twigs having numerous active young scales had to be brought 

 to within about six inches of the mouth of the bellows before any of 

 the insects were dislodged. It thus requires a stronger wind than 



