PIERINAK: I'lERIS UAPAK. 1217 



tlicrc is more tliuii one brood aimiiully, tlie clicek on tlie spread of rapae 

 must be of untold importance to the farmer. 



Before tliis insect was recognized as identical in the two worlds, Mr. Otto 

 Lugrror introduced European specimens into the region ahout Baltimore 

 by bringing with liim tliroe pints of the infested chrysalids from Germany. 



The other European species, Apanteles glomeratus, was first reared by 

 myself in Cambridge, Mass., within a year of the arrival of P. rapae at that 

 point, as it was before I left for Europe in June, 1<S70. At first it was 

 described as a distinct species ; it has now been found as far west as 

 Michigan, and it may be questioned if it too be not indigenous. Hymenop- 

 tcrous parasites of some kind have also been found as far eontli as Georgia, 

 and as early as 187(i (Ocniler). 



Tlic only other hymenopterous parasites known in this country are 

 hyperparasitic ; one, Mesoohorus pieridicola, like the Mesochorus attacking 

 Apanteles in Elurope, larger than its host ; the other a Tetrastichus, reared 

 by Mr. Riley. 



But we have our dipterous parasite also : it was recognized first in 

 Quebec by the Abbe Provancher, and since by many others. It is an 

 Exorista and was described by Osten Sacken under the specific name hirsuta 

 (89:13-15), I had one maggot come out from a chrysalis at the end 

 of June and give birth to the fly after ten days. Dr. Williston thinks 

 this fly mav be identical with one of the European parasites of rapae, in 

 which case all of our direct parasites are the same as the European and 

 fewer in number. 



We have also our spiders which devour the young caterpillars, according 

 to Fitch, and Barnard and others have found the gluttonous Hemiptera, 

 Phymata erosa and Arma spinosa, impaling them while still small. 



Finally it is highly probable that wasps are as detrimental here to the life 

 of this butterfly as in England, where Newport long ago observed the 

 attacks of Vespa vulgaris and gave the following graphic account : — 



"I observed, on a sudden, a specimen of 1'. rapae, towards which I was then looliing, 

 precipitated to the ground from the thistle-blossom upon which it had been very 

 quietly seated ; and upon going up to it immediately. T found a wasp very busily em- 

 ployed in cutting off its wings and head, and aftervvards its legs. When it had done 

 this it took up the dismembered body, and poising it between its own legs, flew away 

 with it to a neighboring tree, where, upon following it, I found it mangling the liody 

 of Its prey, as if to destroy the little remaining vitality. While doing this the 

 wasp had suspended himself upon a leaf by the claw of one leg, which supported 

 its whole weight, while its other limbs were employed in holding and turning the man- 

 gled body of the butterfly. Wlien it had done this sufticiently the wasp rolled up the 

 body between its second and tliird pairs of legs, and poising itself upon its wings, flew 

 away towards its nest. ... Its chief prey .among lepidopterous insects is P. rapae, 

 ."vlthough it attacl\s all the other species of white butterflies. I saw it attempt to cap- 

 ture the fine species, Vanessa atalanta, but the insect was too nimble for it. If it 

 misses its object it does not make a second attack, but flies on to tlie next thistle. 

 (Trans, ent. soc. Lond., i: 228-230.) 



'SJ 



