486 Journal of Agricultural Research voi. xvm. No. 9 



normal, well-fed Calosoma is usually quite full of blood, in contrast to 

 the body of a parasitized specimen containing third-instar larvae. Never- 

 theless the transferred immature larvae all died, while the beetles some- 

 times lived more than a month. These larvae, though they move about 

 freely in the body cavity of a parasitized beetle where the blood and 

 fats have been greatly reduced, can not withstand the sudden change 

 to full-blooded conditions as found in normal specimens. It is probable 

 that they di^d from drowning or suffocation. 



SECOND OR HIBERNATING INSTAR (PL. 58, d) 



Specimens preserved in alcohol ranged from 4.8 mm. long and 1.9 mm. broad to 5.1 

 mm. long and 2.2 mm. broad, or an average of 4.9 mm. long and 2.1 mm. broad. Color 

 white, form elongate. Larva inclosed in light-brownish tracheal "ftmnel" which 

 darkens on exposure to light. Funnel of thin membranous tissue darker and thicker 

 at anal end. Base of ftmnel constricted where it joins walls of trachea and sometimes 

 angled at point of constriction. 



The parasite passes the hibernation period as a half -grown or second- 

 instar larva. It remains attached to the tracheal branches of the meta- 

 thorax in the same position as in the first instar. During July and early 

 August the adults of Calosoma sycophanta begin to enter the earth for 

 hibernation, and some of them contain the first-instar larva of the para- 

 site; this larva transforms to the second instar and then ceases its activ- 

 ity and feeding and becomes dormant soon after the beetle has con- 

 structed a cavity. Activity of the host and that of its parasite are 

 resumed almost simultaneously in the spring. With parasitized speci- 

 mens of C. sycophanta this activity usually occurs in the latter part of 

 May and the first of June. 



THIRD INSTAR (PL. 58, c) 



Color grayish white. Varying in size from 8 mm. long and 3 mm. broad to 9.5 

 mm. long and 3.5 mm. broad, or an average for six alcoholic specimens of 9 mm. long 

 and 3.3 mm. broad. Larva broadest across the eighth or ninth segment, tapering 

 gradually toward anterior and more noticeably toward the posterior end. Each 

 segment except the head is provided with annular spine areas composed of many 

 broken rows of very short black spines, ranging from 6 to 18 rows in each area. These 

 spine areas cover about half the area of tlie segment, the remaining portion being 

 smooth. Mouth hook (PI. 58, B) partly visible, especially the two sharp, curved 

 extremities. Anal stigmata rather widely separated in well-fed larvae. Inner mar- 

 gins almost parallel, rounding at dorsal, ventral, and lateral extremities. Each stigma 

 containing six radial elongate slits. Outer margins of stigmata brownish black and 

 central areas light brown. Stigmata arising out of depression in the anal segment. 

 Larva not found inclosed in tracheal funnel in this stage, as in first and second stages. 



When the larvae have reached the third instar they are found, upon dis- 

 section of the host, in all parts of the body cavity from the prothorax to 

 the tip of the abdomen. After the greater portion of blood and fats 

 has been reduced as a result of the constant feeding of several larvae, 

 the latter move about freely in the body cavity. Their movements 

 increase as the host weakens and approaches death. Feeding and activ- 



