490 Journal of Agricultural Research voi. xvni. No. 9 



204 parasitized beetles collected contained 763 puparia, from which 641 

 flies issued, 122 dying in the pupal stage. The highest number of puparia 

 contained in one beetle was 16 and the lowest i. This gives an average 

 of 3.7 puparia in each parasitized beetle, from which an avera,g^e of 3 flies 

 issued. The data secured in 191 6 showed an average of 3 puparia per 

 beetle, from which an average of 2.8 flies issued. 



All adults of Calosoma sycophanta collected in the field for colonization 

 purposes in 1 9 1 7 and 1 9 1 8 were examined individually for eggs of the para- 

 site as soon as they arrived at the laboratory. Although the eggs hatch 

 in a short time, the chorion sometimes remains glued to the beetles for a 

 few days. A total of 5,707 adults were collected in 191 7 between June 20 

 and July 24. Five beetles were found containing eggs of the parasite on 

 the following dates: June 23, June 25, and July 6. During 1918, 6,072 

 adults were collected in the field between May 2 8 and July 1 9. Two beetles 

 containing eggs were collected on June 5 and July 3. Those eggs found 

 on June 5 apparently were deposited by flies of the winter generation 

 and those of July 3 by flies of the summer generation. 



PARASITES BRED FROM FIELD COLLECTIONS OF CALOSOMA CALIDUM 

 FAB., CALOSOMA FRIGIDUM KIRBY, AND CARABUS NEMORALIS 

 MULL., 1912-1918 



Small collections of adults of Calosoma calidum Vah., Calosoma frigidum 

 Kirby,and CarabusnemoralisMuW. were made almost every year in eastern 

 Massachusetts and southern New Hampshire between 1912 and i9i8and 

 confined in jars of earth at the laboratory. From them specimens of Eubio- 

 myia calosomae were bred occasionally. Since some of the early rearings 

 from these collections were more or less accidental, it is thought advisable 

 to give the percentage of parasitism as based on the total collections of 

 each species for the 7-year period. During this period 92 specimens of 

 Calosomu calidum were collected, 3 specimens, or 3.3 per cent, of which 

 were parasitized. A total of 238 adults of Calosoma frigidum were col- 

 lected, of which but i, or 0.42 per cent, yielded parasites; and 169 adults 

 of Carahus nemoralis were collected, i of which, or 0.59 per cent, was 

 parasitized. It might be added that in 191 2 when 49 adults of Calo- 

 soma calidum were collected, 3, or 6 per cent, yielded to parasitism and 

 in 191 5, when only 3 adults of the same species were collected, i, or 33 

 per cent, later died of parasites. 



These records tend to indicate that the parasite is slightly more effective 

 on Calosoma calidum^ than on C. sycophanta. This may explain in part 

 why the former species is less common in New England than formerly. 



LIFE-HISTORY STUDIES 

 OVIPOSITION 



The eggs are deposited by the female on the exterior surface of Calosoma 

 adults, being glued to several parts of the exoskeleton. They are deposited 

 singly and in patches of 2, 3, and 4. Eggs have been found attached to 



