8 
BULLETIN 116. 
from their neighbors. Young lice have been known to appear upon 
box elder before maple. 
The newly hatched young remain a day or two in the ovisac and 
then migrate to the leaves where they attach themselves to the ribs or, 
rarely, to the young twigs. In doing this they prefer the under sides 
and larvse so situated appear to grow more rapidly than those other¬ 
wise located. In times of serious infestation these locations soon be¬ 
come preempted and the young swarm over every green thing within 
a short radius of their home. It is in these cases that the summer food 
plants serve as hosts. On some of these they seem to prosper fairly 
well. Dr. Forbes found that the males reached maturity on straw¬ 
berry plants, and, as an isolated maple tree which had been thoroughly 
treated during the summer was reinfested in the fall, concluded that the 
females had found their way back from temporary food plants. 
Shortly after the young begin to feed a delicate waxy scale forms 
over the back. 
The first molt occurs in from three to four weeks from the hatching 
of the egg. It was observed in Washington as early as June 10. At 
this time the insects are about twice their size at hatching. 
After this molt the differences in the sexes is observable. “The 
males grow more slender and soon cease to increase in size, covering 
themselves with a thin coating of wax.’’ At this stage, according to 
Howard, the second molt takes place beneath the scale and a propupal 
stage occurs. (See Fig. 3.) 
Fig. 3. PULVINARIA IMMUMERABILIS : a, adult male ; b, antennae of same ; c, leg of 
same; d, second stage of pupa; e, cast skin of same; f. true pupa ; g, cast skin of same 
All greatly enlarged, b and c still more enlarged. (Howard Bui. 22, Div. of Ent< m., 
U. S. Dept. Agr.) 
“In a few days the pupa casts its skin and assumes the true pupa form, which, 
during its earl ier stages is a pale green color, becoming dark flesh color at a later date.” 
“The antennae which up to this time were seven-jointed, had now become eight- 
jointed. There seemed to be two propupa stages. After casting the second skin, 
