PARASITIC ENEMIES OF TREES AND PLANTS 



493 



changes to a warm mahogany red, and is not altogether 

 an unpleasing object. (Fig. 5). I have found that the 

 stems of the plant invariably die distad to these masses, 

 but they may 



pass through the maple woods during the spring and 

 summer months, yet not one person in an hundred can 

 say how they came there. They are well shown in my 



r e p r o d u ced 





live and bear 

 flowers and 

 fruit below 

 them ; this is 

 well shown in 

 the big middle 

 one in the plate. 

 On cross sec- 

 tion i t h e r 

 way and at any 

 point one of 

 these masses is 

 found to be 

 quite solid, 

 with perfora- 

 tions here and 

 there that lodge 

 the larvae of 

 the parasitic in- 

 sect responsible 

 for the forma- 

 tion of the gall. 

 Not infrequent- 

 ly one of these 

 masses is com- 

 posed of some 

 five or six long- 

 itudinal parts, 

 roughly subcyl- 

 indrical in form 

 with rounded 

 more or less 

 pointed, extre- 

 mities. They 

 are closely 

 packed togeth- 

 er and sur- 

 round the stem, 

 as illustrated in 

 not a few 

 works on the 

 subject. Still 

 others of these 

 galls are round- 

 ed and nodular, 

 as shown in 

 Figure 5. 



Next we 

 come to the 

 beautiful little 

 galls so fre- 

 quently seen on 

 the upper side of the leaves in the red maple {Acer 

 rubrum). No end of people see these every day as they 



wombicxA ^\ 



INSECT THAT MAKES THE OCELLATED RINGS ON MAPLE LEAVES 



Fig. ii^Copied by the, author from a plate in one of Packard's Reports. The original 

 drawing by Mrs. A., B. Cofflstock, of Cornell University. (Mucli enlarged). Sciara 

 ocellaris. I. Leaf of maple (Acer rubrum) with galls; 2. adult, male; 2a., tibial spurs and 

 brushes of same; 2b, claspers of same; 3, larvae; 3a, head of larva; 3b, caudal end of 

 larva ; 4, cocoon and pupa skin. 



photograph of 

 them in Figure 

 0, where two 

 leaves of a red 

 maple present 

 the infection. 

 Each of these 

 ocellated spots 

 has a diameter 

 o f something 

 like three- 

 eighths of an 

 inch and is bril- 

 liantly colored, 

 the center and 

 outer ring be- 

 ing of a bright 

 red, with the 

 included ring a 

 deep, rich yel- 

 low. Sometimes 

 nearly every 

 leaf on a red 

 maple may be 

 t h u s affected 

 and the tree be 

 terribly dam- 

 aged by the 

 condition while 

 in some in- 

 stances only a 

 few of the 

 leaves present 

 these galls and 

 the tree does 

 not suffer in 

 any way. In 

 the red maple 

 woods abou)t 

 Wa s h in g t on 

 one frequently 

 finds examples 

 of this condi- 

 t i o n of the 

 leaves, now 

 known to be 

 caused by a mi- 

 nute insect. 

 Sometimes the 

 spots are of 

 but one color, 

 that is, of a 

 pale green, or, in others, a light yellow. As many as 

 fifty may occur on any single leaf, in some cases being 



