of the bluegills ate from 8 to 11 larvae in addition to the 

 poisoned adult flies, and survived an additional 7 days, -when the 

 experiment was concluded. Some of the fish showed definite DDT 

 tremors', but later recovered. 



Six bluegills and six black crappies averaging 31 ram., in 

 length were placed together in each of £>ur aquaria. The fish in 

 two aquaria devoured midge larvae, treated with wet table DDT, in 

 fairly constant numbers for the first 3 of 4. feeding days, and 

 the fish in two control aquaria received untreated larvae. The 

 water temperature averaged 72° F. Altogether 278 treated larvae 

 were fed one group and 637 to another, whereas the two control 

 groups each took 425 untreated larvae. The fish consuming the 

 least number of treated larvae died first. Eleven fish in one 

 aquarium succumbed three to four days after the first feeding. 

 Seven in tne second aquarium died 4 to 5 days after the first day 

 of feeding; in addition, four died 7 to 8 days later. All of the 

 control fish were alive at tiie end of the 12-day experiment. Since 

 about equal numbers of bluegills and crappies died, there was no 

 noticeable difference in susceptibility to DDT between the two 

 species. 



Consumption by Largemouth Black Bass of DDT-Sprayed Insects 



Pour largemouth black bass, 83 mm., in length, -were placed in 

 8 inches of water in each of three Fearnow pails. The fish in two 

 pails were fed 241 and 271 housefly maggots treated with wettable 

 DDT (formula 1) over a period of 7 days, while the control fish 

 consumed 200 untreated maggots . The temperature of the water dui^ 

 ing this experiment averaged 68° F. Of the bass receiving treated 

 larvae all died 2 to 4 days after the cessation of feeding, urtiereas 

 all of the control fish survived. 



In another experiment four largemouth bass 52 mm., in length 

 were placed in each of eight aquaria. The fish in six aquaria were 

 fed all the treated housefly larvae (sprayed with wettable DDT. 

 formula 1) that they would eat on two successive days (table l). 

 Two controls were fed untreated larvae. After the second feeding, 

 those aquaria in which the fish ate approximately tne same number 

 of larvae were grouped in pairs . The fish in one aquarium in each 

 group were fed untreated larvae during the next 12 days while the 

 fish in the other aquarium of each group were fasted. Ihe two con- 

 trols were fed untreated housefly lairvae throughout the feeding 

 period. Water tempera tvo-es in the aquaria averaged 70P F. Eight 

 of 24 bass fed the treated larvae at the beginning of the experi- 

 ment died. Five of tnese deaths occurred in tiiose aquaria where 

 the fish were fasted. 



