New York Agricultural Experiment Station. 583 



This is called incomplete metamorphosis and is found to occur in 

 true bugs and locusts. 



In the scale insects, which belong to a family of true bugs, we 

 find both forms of metamorphosis. The male undergoes the com- 

 plete and the female the incomplete transformation. Hence in the 

 plum scale we must look for a decided diii'erence ini^appearance in 

 the male and female scales, although the difference is not readily 

 apparent in the larval forms. 



The Egg. — Fig. 12 represents some of the eggs greatly enlarged. 

 The eggs average about 0.3 m. m. in length and are oblong oval in 

 shape and rounded at the ends. The shell is smooth. At first they 

 are white in color but Mr. Slingerland has observed that they 

 " become pinkish in color about a w^eek before hatching." 



The eggs are laid under the mother shell. Indeed it may be said 

 that the mother literally turns into a mass of eggs, as but little more 

 than the integument finally remains, which, as previously noted, forms 

 the brittle oval shell. Egg laying begins about the middle of May. 

 Mr. Slingerland notes * that in 1894 eg^ laying began by the 18th of 

 May. June 28 (1895), the writer found at Hector an occasional 

 female scale just beginning to lay eggs, indicating that the time 

 for egg laying may vary over a month in individual cases. The 

 period of incubation varies considerably in western JNew York. 

 June 24 (1895), Mr. Beach wrote that the Lecanium eggs were 

 hatching. June 28 the young scales were quite abundant in infested 

 plum orchards at Geneva. Eggs from scales on fresh plum twigs 

 sent to Jamaica and kept in the laboratory, hatched June 21. 



The number of eggs laid by a single female is astonishing, varying 

 it is said, from less than one thousand to several thousand. The 

 writer counted two thousand one hundred and thirty eggs under a 

 sing-le female of averasce size. 



The Larva. — The newly -hatched larvae remain under the mother 

 shells for a time varying from a few hours to tw^o or three days.f 

 Fig. 13 represents one of these larvae viewed from the under sur- 

 face. At this time they vary in size from ,02 to .03 of an inch in 

 length, and axe a little more than half as broad as long. If 

 examined carefully, a side view will show that they are very thin 



* Bulletin 83, Cornell Agricultu-al Experiment Station, p. 690. 



t Young scales r^'ared in the laboratory did not come forth from the mother shells until 

 three days after hatching. 



