PUTNAM ON PULVINARIA INNUMERABILIS. 331 



THE EGG NEST. 



The egg nest is formed of cylindrical white fibres or filaments of wax, 

 secreted by the peripheral spines of the mother louse, its posterior end 

 being constantly pushed farther and farther back by the crowding of 

 the moie recently laid eggs, and the continued secretion of the waxen 

 fibres. The eggs first laid are thus found at che end farthest removed 

 from the insect. The waxen fibres are quite adhesive to one another, 

 forming a perfectly close covering to the eggs, which however separates 

 quite easily along the median line— showing that no waxen filaments are 

 secreted from the anal fissure. This fibrous structure causes the nest 

 to appear faintly striated longitudinally, and the successive layers of 

 eggs often make it appear somewhat coarsely waved transversely, with 

 the waves approximately parallel to the posterior periphery of the abdo- 

 men. Permeating all through the nest are filaments secreted by the 

 sub-abdominal spines, and a quantity of powdery matter, the secretion 

 of the sub-abdominal pores. When highly magnified this dust is seen to 

 be in the form of rings. Under ordinary circumstances tlie egg nest 

 extends to a distance beyond the tip of the abdomen, equal to from once 

 to more than twice the entire length of the mother. The waxen fila- 

 ments are adhesive and very elastic so that the fibres of the egg nest can 

 be pulled out six inches or more. They melt upon the application of heat 

 are soluble in alcohol, chloroform, ether, turpentine, oil, etc., and inso- 

 luble in water, glycerine, nitric acid, etc. 



LAST DAYS OF TUE FEMALE. 



Soon after the middle of May the female begins to lay her eggs, envel- 

 oping them in a nest of white waxen fibres, forming a beautiful white 

 cushion — whence the name of Pulvinaria. This gradually raises the ab- 

 domen of the female from the bark until often an angle of 45° or more 

 is reached (figs. 39, c; 41 ; 42), causing the back to become more or less 

 transversely wrinkled. The laying of tlie eggs continues often into the 

 early part of July, the entire laying period lasting from five to seven 

 weeks, varying somewhat with the seasons, the health of the trees 

 and of the insects themselves. Her beak remains inserted in the bark all 

 the time absorbing the sap. The entire number of eggs laid in each 

 nest is rarely if ever less than 500, and must often exceed 2,000, thougli 

 as I have not attempted to count the number in the larger nests this is 

 only an estimate.* In fact the mother continues to lay eggs until she 

 dies from her own sheer exhaustion, or that of the tree upon which she 

 dwells, with her ovaries still filled with ova in all stages of development. 

 The entire life of the female from her birth to her death is thus about 

 thirteen months. The length of time elapsing after impregnation by 

 tiie male until the first eggs are laid is fully nine mouths— but of tliese 

 at least five are passed in a dormant state. After the females have died 

 they dry up and the beak breaks off, but they still continue attached to 

 the limb by means of the egg nests which remain frequently for a year 

 ■or more. 



*Dr. S. S. Rathvon states, in his pcaper in Perm. Farm Journal, 1854, that he counted in 

 >one of tliese nests 564 livinst insects and over 300 e<!;£rs not hatched. 



