THE HABITS IN OVIPOSITION OF THE 

 BEETLE BRUCHUS 



J. ARTHUR HARRIS 



Station for Experimental Evolution, Cold Spring Harbor, N. Y. 



Beetles belonging to the genus Bruchus may either deposit 

 their eggs upon the outside of the young pods of large-seeded 

 legumes (Phascolus, Pisum, Vigna, Vicia and others) through 

 which the young larvae penetrate to the developing seed, or 

 upon the surface of the dry, stored seed. 



If the behavior 1 of the insect in oviposition be dependent in 

 any degree upon the characteristics of the young pod, such 

 modification of behavior as may take place because of the vary- 

 ing characteristics of the developing ovary may (although it 

 will not necessarily) be recorded in the differences in the inci- 

 dence of parasites as determined from samples of matured seeds 

 drawn from pods of known matured characteristics. One can- 

 not assert upon failure to find a relationship between the char- 

 acteristics of matured pods and the incidence of parasites that 

 some such relationship does not exist in the case of the young 

 pods. On the other hand, a relationship actually demonstrated 

 on the basis of matured pods only should be interpreted with 

 caution. These statements are true for the reason that the 

 degree of agreement between the characteristics of mature and 

 developing pods is not fully enough known. It is here that 

 direct observations upon behavior seem almost indispensable. 



The analysis of the data- for two experiments, involving 



1 These dates were secured in connection with some physiological work on seed 

 weight in beans in which it became necessary to consider the question of the inci- 

 dence of Bruchus o-tectus in experimental cultures of Phaseolus made several years 

 ago. They are presented in full in the Journal of the New York Entomological 

 Society, December, 1915. The purpose of this note is to call the attention of students 

 of animal behavior to an addition to the list of instances in which records made 

 by the organism itself may greatly facilitate the study of behavior, and to the 

 need for direct observations upon behavior supplementing the data here given. 



2 The seeds studied were parasitized almost exclusively by insects developing 

 from eggs on the pods in the field. I cannot assert that none were parasitized in 

 storage, but if an appreciable number were so injured it makes the results here 

 given even more significant, since any random injury would tend to obscure differ- 

 ential parasitization. 



