6 WHEELER— THE PARASITIC ACULEATA. 



Graenicher's observations are more extensive. He studied in 

 Wisconsin the parasitism of Stelis 6-maciilata on Alcidamia pro- 

 ducta, of Coclioxys lucrosa on Megachile addenda and of Triepeo- 

 liis helianthi on Melissodcs trinodis. In all these cases the general 

 behavior of the parasite is very similar to that of Stelis niinuta and 

 ornatitla, but he found that the just-hatched larva has sharp, falcate 

 jaws, which are very large in Calioxys and Triepeolus and are re- 

 placed by smaller jaws with the next moult, after it has killed the 

 host larva. The first stage Triepeolus larva, moreover, has pecu- 

 liar leg-like appendages which enable it to crawl about in the cell. 

 We are justified, therefore, in speaking of a hypermetamorphosis 

 in these bees, comparable to that of so many other parasitic insects 

 (Rhipiphoridse, Strepsiptera, Meloidae, Eucharine Chalcididse, 

 Chrysididas, Mantispidse, etc.). I quote a portion of Graenicher's 

 account relating to the Stelis larva. 



"July 9, 1903. Nest collected at Milwaukee contains 4 cells. Third cell 

 (from below) with a parasite. On top of the bee-bread an Alcidamia larva, 

 about 3 days old. On the side of the bee-bread, about half way up a Stelis 

 larva feeding on bee-bread. It is smaller than the host larva, and its head is 

 directed upward, and toward the posterior end of the latter's body. 



" July 13. The parasitic larva has grown considerably but is not as large 

 as the host larva. At i P.M. the parasite moves upward a short distance, 

 comes in contact with the host larva, and secures a hold on the latter's side 

 behind the middle of the body. The victim at first makes an effort to free 

 itself, but offers no serious resistance. The parasite remains in the same 

 position the whole forenoon, sucking the liquid contents of the host's body. 

 The latter gradually perishes and shrivels. 



" July 14. The parasite has released its hold on the dead host larva, and 

 is feeding on bee-bread. It has lately increased very much in size. From 

 now on the parasite does not pay any more attention to the remains of 

 the host. 



" In the cell just considered a single parasite was present, but in a nest 

 collected at Milwaukee, July 15, 1903, a cell was come across with 3 parasitic 

 larvae, all of them on the same side of the bee-bread as the head of the 

 host larva. One of them was sitting above the middle, not far below the 

 host larva, the second was lower down and directed laterally, and the third 

 was below the second and quite close to it. In the evening the third parasite, 

 which throughout the day (July 15) had been partaking of bee-bread and 

 growing in length, reached the second and killed it. Four days later this same 

 parasite killed the uppermost one and fed on its contents. Two days after 

 this (July 21), the surviving parasite killed the host larva. Both were about 

 equal in size." 



