62 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



In a dark-room in which the temperature and relative humidity 

 were fairly constant many tests were conducted to determine the differ- 

 ence between the phototactic and geotactic responses of adult bean 

 beetles and their larvae, with and without the use of light. The in- 

 sects were confined in a photo-geotactic box, just above or below 

 which lay a water screen to prevent the infra-red or heat rays from 

 reaching the beetles. Under these conditions the following results 

 were obtained. For active, overwintering adult beetles the geonega- 

 tive or upward response, when light was used, was 25.6 ±0.20 per cent 

 stronger than the geopositive or downward one ; but when no light 

 was used, it was 54.6 ±0.17 per cent stronger, indicating that when 

 the beetles were forced downward by the light this stimulus overcame 

 about one-half of the geotactic one. Old beetles of the second brood 

 did not respond so readily, yet their geonegative responses were 

 stronger than their geopositive ones. Larvae of the third instar did 

 not respond readily and they went up only slightly more than down. 

 When light was used, active larvae of the fourth instar reacted as 

 readily as did the overwintering adults ; but when no light was used, 

 they did not respond so readily, although they went up more than 

 down. 



While searching for attractants and repellents an improved feeding 

 method was devised. The adult bean beetles were confined in four 

 small wire-screen cages, each of which contained a row of the same 

 four foods, but differently arranged. This series of tests, with the 

 foods differently arranged each time, was then repeated three times in 

 the forenoon, and usually the four series were again repeated in the 

 afternoon. Each individual food used was therefore tested 16 times 

 in the forenoon and usually 16 times in the afternoon. According to 

 the arrangement of food, no two rows in the same cage were exactly 

 alike; likewise, no two rows of all 16 rows were identical, although 

 the distribution of food was not so complete. This plan was adopted 

 in order to equalize the number of beetles counted on the same food 

 which lay in all four positions during any one series of tests ; and 

 furthermore, everything possible was done to obtain reliable data 

 which could be treated statistically. Using this plan the following 

 results were obtained. 



To determine whether bean beetles " like " or " dislike " the four 

 classes of substances which produce the four human attributes of 

 taste, many series of tests were conducted. It was soon learned that 

 they have " likes " and " dislikes " in regard to food. They " dis- 

 liked " water containing salts, acids, bitter materials, and saccharine ; 

 but " liked " the other sweet substances tested, including cane sugar, 



