The European Elm Scale 13 



NEWLY-HATCHED LARVAE 



Total length of body approximately .41 mm. Breadth, .21 mm. 

 Outline oval, twice as long as broad, tapering posteriorly to two fleshy 

 lobes each of which bears three stout dorsal spines and a long terminal 

 filament whose length equals half that of the body. Color, lemon- 

 yellow. Entire lateral margin of dorsum fringed with stout, thick 

 spines. Of these each abdominal segment bears two. Along the tho- 

 racic and interior margins the bases of the lateral spines are set higher 

 up on the dorsum. Between the antennae the row is made double by 

 the addition of four spines whose bases are marginal in position. 

 There are two such spines on the ventral surface between the bases 

 of the antennae, curved a little and directed forward. The dorsum 

 bears a double central row of paired spines of the same shape and gen- 

 eral character as the lateral ones. Of these dorsal spines, pairs seven 

 to ten inclusive and often pair eleven also are reduced to rudiments. 



The antennae are stout and fleshy, the division into segments not 

 strongly marked. Their length is to that of the body as 11 is to 19. 

 They are six-jointed, the sixth segment is longest. Its length is to that 

 of the third segment as 27 is to 22. It bears a number of short hairs 

 and two longer ones whose length is to that of the segment as 61 to 27. 



Of the leg-segments the femur is the longest, the tibia shortest. 

 The lengths of femur, tibia and tarsus are to each other as 65, 37 and 

 5-4. The anal ring is surrounded by six hairs. Plate XII. 



RATE OF INCREASE 



Toward the end of the season a little mass of delicate egg-shells 

 has accumulated in the waxen cradle of the female ; and it would seem 

 as though one might form a good idea of the number of eggs laid 

 by one female simply by counting the shells. I reached in this way 

 no satisfactory result, however, partly because of the difliculty of sepa- 

 rating and counting things so small and fragile and partly because of 

 the fact that some of the shells are lost when the body of the female 

 shrinks toward the end of the laying season. Then, too, larvae which 

 have become entangled with the shells drag some of them out when 

 they make their escape. 



In another way we may reach an unsatisfactory idea of the number 

 of eggs laid by a single female. In some instances the vitality of the 

 larvae is so low that they cannot escape from the semi-cocoon and die 

 there shortly after birth. In such instances from sixty to nearly three 

 hundred larvae have been counted beneath a single female. 



