THE CITRUS MEALY BUG 303 



LIFE HISTORY. 



Very little has been dune toward the working out of the life histor\- 

 of the citrus mealy bug. In fact, as yet, no one has followed it at all in 

 its various stages in the orchard. Mr. G. C. Davis, of the Agrc. College, Mich., 

 has worked out the following in the greenhouse, and published it in Insect Life. 

 vii. No. 2, p. 168 (1894). 



"The female of uur commonest mealy bug, Dactylaf^iiis destructor (now 

 Pseudococcns citri ) is very prolific, laying usually not more than 400 eggs, 

 Init may vary in number from 300 to 600. Each egg is slightly oblong and 

 ;d50ut 0.25 mm. in length. The color is light straw yellow, with small parti- 

 cles of the white waxy secretion covering each one. Over the whole egg 

 mass is a white flocculose network of waxy threads which cover the eggs and 

 quite effectually protect them from attack by other insects. The female com- 

 mences secreting these threads some hours before egg laying begins, and 

 continues secreting as long as the mass of eggs increases. A female before 

 laying her eggs will be about 2.5 mm. wide and 4 mm. long, but when through 

 there is nothing left of her but a little dry wrinkled piece of lifeless skin 

 and a mass of eggs back of her that will measure two or three times as niuch 

 as she did a short time before. The female feeds all the time she is depositing 

 her eggs, and no doubt lays far fewer eggs when forced to do so with no 

 food accessible. The eggs first laid will remain farthest from the female 

 and beneath, she moving ahead as the mass grows. The mass also raises 

 her until toward the last her position is often nearer vertical than horizontal." 



"Quite a number of females of various sizes were placed in a jar to 

 see how long they would live with no food. There was moisture enough for 

 their needs, and the temperature was a little above what it would be in a 

 comfortable dwelling house. The smaller ones, which were not over a quarter 

 grown, moulted on the second day and on the third were mostly dead. 

 Many of the larger ones moulted the day the smaller ones died. Some of the 

 smaller of them lived a few days longer and then died, but the most of the 

 larger ones began very soon to deposit eggs. One of the largest of the 

 number was carefully watched, and it was found that the eggs increased at 

 (he rate of about 36 every twenty-four hours. Kgg laving lasted onl\' four 

 or five days, instead of ten days or two weeks as usual, when the female 

 shriveled and died, leaving from one hundred to one hundred fifty in each 

 mass. The most of these eggs were fertile and hatched in about a week after 

 they were placed there. None of the females were full grown, and the ex- 

 periment shows that the mealy bug will still strenuously endeavor to propa- 

 gate its k'ind from immature specimens when food is wanting. .\nother 

 lot of specimens were placed in a cold room under otherwise similar con- 

 ditions and all sizes remained dormant for a long period with no a])parent 

 mjury." 



"Tt requires from one to two weeks for the eggs to hatch, according 

 to the temperature. .\s a usual thing the young mealv bugs from the eggs 

 fn-st laid will hatch s<inie days before the female has finished laying. Thev 



