October, '15] 



CLAUSEN: APHID-FEEDING COCCINELLID^ 



491 



was 624 aphids for 0. oculata, and 234 as a minimum for C. sanguinea. 

 One adult of the former species devoured 672 aphids during this period. 

 On a daily basis the variation extended from 56.1 aphids per individ- 

 ual for H. convergens to 15.6 for C. sanguinea, C. californica was 

 conspicuously low in this respect when the size of the beetle is consid- 

 ered, the average being onlj^ 34.0 aphids per day. 



Feeding Records 



Larv£e 



Adults 



Species 



No. of 



Specimens 



Length 

 of 



Aphids Eaten 



Period Daily 



No. of 



Specimens 



Length 



of 

 Period 



C. cdifornica Mann 

 C. irifasciata Linn. . 

 H. convergens Guer. 

 H. ambigua Lec. . . 

 0. ahdominalis Say. 

 0. oculata Fabr. . . . 

 A. hipunctata Linn.. 

 C. sanguinea Linn.. 



23.7 da. 



25.8 



23.8 



27.7 



16.7 



25.2 



21.7 



20.0 



475 

 294 

 349 

 312 

 240 

 326 

 252 

 216 



24.9 

 15.8 

 20.7 

 11.4 

 19.8 

 17.2 

 14.1 

 14.5 



On the basis of the results secured in the studies previously outlined, 

 the following conclusions may be drawn: 



1. Temperature and humidity are very strong controlling factors 



in the development and behavior of the different species. 



2. The number of eggs deposited under normal field conditions varies 



from 200 to 500 and occasionally more, extending over a period 

 of four to eight weeks in case the female lives the full adult life. 



3. The period intervening between emergence and mating is one to 



three days, and from mating to oviposition eight to eleven days. 

 A period of ten to fifteen days thus intervenes between emerg- 

 ence and the beginning of oviposition. 



4. Oviposition normally takes place daily, with occasional exceptions. 



5. The number of aphids eaten by the larvae of the different species 



varies approximately with the size of the individuals, the num- 

 ber varying from 216 to 475 for the entire larval period. 



6. The above to a somewhat lesser extent is true of the adults also. 



President Wilson: The next paper is by Mr. J. F. Illingworth 

 and will be read by Mr. 0. H. Swezey. 



