195 



A noteworthy incident of natural insect control occurred re- 

 cently when the eggs of a Pierid were parasitized hy a small 

 H\ inenopter to such an extent that the ravages of the last genera- 

 tion of this insect were rendered negligible. 



The eggs of this Pieridae are deposited singly on the under side 

 of the leaves of Cassia siamea Lam. Upon hatching, the larvae 

 have heretofore, during the course of their development, com- 

 pletely defoliated the trees which they had attacked. 



During November of last year eggs were noticed to have been 

 deposited liberally on the leaves of these trees ; some were taken 

 to be bred in the laboratory, and preparations were made to spray 

 the trees when the eggs should have hatched. The collected eggs 

 hatched, but those on the trees did not. Upon examination the 

 latter were all found to be parasitized. 



PLANTS RESISTANT TO INSECT ATTACK. 



Plants often resist insect attack by "abnormal" growth and by 

 exuding a sticky sap or other similar substance. A noteworthy 

 instance of a plant resisting the attack of insects occurs in the 

 seed heads of lettuce (Lacfuca safiz'a L.). Upon the slightest 

 touch to lettuce seed heads this plant exudes a milky, sticky sub- 

 stance, and when the insects alight upon it they are immediately 

 fastened to the plant, and in their efforts to get away the plant is 

 disturbed still more, causing it to throw out still greater quantities 

 of this protective latex, till at last the insects are held rigid and 

 thus soon die. Lately, at Singalong, it was noted that the lettuce 

 seed buds were covered with dead insects, including the following: 



Pentatomidae : A'a:::ara viridula Fabr. ; Eitrydciiia pulclirum 

 Westw. 



Phrrhocoridae : D\sdcrcus siiii^uJatns L. ; D\sdcrciis pocdilns 

 H. S. 



Capsidae : One species ; Hymenopterous parasites, four spe- 

 cies ; Diptera and Microdiptera, five species. 



Chrysomelidae : Aidacophoro coffcae Hornst ; one other species. 



Lygaeidae : One species. 



Reduviidae : One species. 



