. Bulletin. the genus Uropoda. All of themites we have collected on May-beetles are in the nymphal migratorystages, in which they attach themselves to the beetles as a means of car- 103 riage, and are probably neither parasitic nor predaceous. When asuitable breeding ground is reached the mites drop and transform, andbegin to feed on bacterial and fungous growths. Parasites of the beetle Oetalid Flies(Pyegota undata Wied. and P. valida Harris) Our earliest record of P. undata as a parasite of Phyllophaga aduUswas made by Prof. F. M. Webster, who reared it in the spring of 1S91from beetles coll
. Bulletin. the genus Uropoda. All of themites we have collected on May-beetles are in the nymphal migratorystages, in which they attach themselves to the beetles as a means of car- 103 riage, and are probably neither parasitic nor predaceous. When asuitable breeding ground is reached the mites drop and transform, andbegin to feed on bacterial and fungous growths. Parasites of the beetle Oetalid Flies(Pyegota undata Wied. and P. valida Harris) Our earliest record of P. undata as a parasite of Phyllophaga aduUswas made by Prof. F. M. Webster, who reared it in the spring of 1S91from beetles collected at Lafayette, Ind., and the first published recordis that of Dr. Forbes in 1907 (26). P. valida was first reared and re-corded by the writer in 1913 (15), and we have since reared it manytimes. The life histories of the two species are substantially alike. Thebeetles are attacked only at night while they are feeding, or in flight,the Pyrgota fly alighting on the back of the beetle, which if feeding is. Pyrgota undata \\ usually sufficiently disturbed to cause it to drop, at the same time spread-ing its wings to break the fall. The fly immediately takes advantageof this act to thrust its ovipositor through the exposed thin abdominalwall beneath the wing covers and to lay an egg in the abdomen. Theabdomen and ovipositor of Pyrgota are admirably adapted to this act,the former being curved, with the tip hard and conical, and the oviposi-tor being a fleshy muscular organ of medium length with a sharp-pointedchitinous tip (Fig. 31). 104 The eggs are elliptical, measuring .05 mm. by mm., and purewhite (Fig. 33). Counts of eggs in the bodies of two specimens of , made May 39, 1911], gave 54 and 98 respectively. The length ofthe egg stage has never been determined by us, but it is probably onlyfive or six days, since the beetles are killed by the maggots within tendays or two weeks after being attacked, and the average length of theegg and larval stages coml^ined is ab
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