Kenneth M. Smith 55 



effect was produced, but on a magnified scale. The salivary glands of 

 P. rugicollis and of Lygus pabulinus, a bug harmful to potato foliage, 

 when placed on a freshly cut slice of potato in a petri dish, produced a 

 violent reaction which killed much of the tissue surrounding the glands. 

 The same experiment was carried out with the glands of one of the 

 harmless apple-feeding bugs Psallus ambiguus, these had no effect what- 

 ever on the potato. When the salivary glands of P. rugicollis were 

 pricked into apple buds, the shoots were killed within 24 hours. The 

 salivary glands of P. ambiguus when similarly treated had no effect. 

 Observations were made showing the rate of exudation of sap from the 

 bug's puncture in the potato and these are given for P. rugicollis and 

 Lygus pabulinus. A list of common plants and fruit trees with their 

 various reactions to the feeding of harmful bugs is also given. 



BIBLIOGRAPHY. 



( 1 ) Fryer, J. F. Preliminary note on the damage of apples by Capsid bugs. Annals 



of Applied Biology, i, No. 2, 1914. 



(2) Petherbridge and Husain. A study of the Capsid bugs found on apple trees. 



Ibid., IV, No. 4, March, 1918. 



(3) Collinge, Walter E. Remarks upon an apparently new apple pest. Journal 



of Economic Biology, June 1912, vti, Part 2. 



(4) Aw ati, P. R. Mechanism of Suction in the Potato Capsid Bug, Lygus pabulinus. 



Proceedings of the Zoological Society of London, September, 1914. 



(5) Stahl, C. F. and Carsner, Eubanks. Obtaining Beet Leaf Hoppers Non- 



virulent as to Curly Top. Journal of Agricultural Research, xiv, No. 9, 

 Washington, D. C, August, 1918. 



(6) Horne, A. S. and Lefroy, H. M. Effects produced by Sucking Insects and 



Red Spider upon potato foliage. Annals of Applied Biology, i, Nos. 3 

 and 4, January, 1915. 



(7) Crosby, C. R. The apple red bugs. Cornell University. Agricultural Experiment 



Station of the College of Agriculture, Bulletin 291, January, 1911. 



EXPLANATION OF PLATE III 



Fig. 1. Photograph of four apples, showing the typical damage produced by Plesiocoris 



rugicollis. Note the "scab" effect. 

 Fig. 2. Photograph of four slices of potato. A, B damaged by L. pabulinus, C by 



P. rugicollis and D fed upon by Psallus ambiguus, but undamaged. In A, B, note the 



large punctures surrounded by dead and blackened tissue. 



EXPLANATION OF LETTERING. 



An. Antenna. C.R. Collapsed Reservoir. Lbr. Labrum. Lb. Labium. Md. Mandibles. 

 Mdl. Mandibular lever. Md.C. Cavity of the mandibles. Md.H. Hooks of Mandibles. 

 Mx.St. Maxillary Stylets. R. Reservoir. Sd. Salivary duct. Sg. Salivary gland. 



