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THE AMERICAN NATURALIST [Voi XLI 



changed color only slightly if at all. Two days later the eggs 

 which had changed but little up to the time of the previous exami- 

 nation were as dark as the rest and indistinguishable from them 

 as far as appearance was concerned. Parasites developed to 

 maturity in each of these ten eggs and the first one was noted to 

 have emerged at noon on October 16th. 



Development in infertile host eggs. It is the writer's observation 

 that shriveling of the eggs of pentatomid bugs indicates infertility 

 although in some species, as in that of the Harlequin Cabbage 

 Bug {Murgantia histrionica), a slight shrinking normally occurs 

 just before hatching. With this as guide for the experiment, a 

 batch of ten eggs was selected, which had been deposited by a 

 specimen of Enschistus servus which previously had deposited a 

 batch of infertile eggs. Four of these eggs were reserved as con- 

 trols and a female parasite was given access to the remaining six; 

 after having made the usual examination she was observed to 

 begin oviposition. The four control eggs shrivelled in the course 

 of a few days, but the six eggs into which the parasite had ovi- 

 posited became dark in color and to all ai)pcarances promised to 

 produce adult parasites, ^one appeared however nor did shrink- 

 ing occur, and several weeks later when the eggs were oi)ened 

 their contents was found to consist of a very dark colored vitelline 

 membrane toi^otliM uidi a ^,,,..11 shrivelled blackish mass on one 

 side, Avhich vva. nun < o.i.. ..l.l< as insect remains. A si,nilar 

 condition was found oc( asionally in parasitized eggs lu'lieved to 

 be fertile and belonging to a batch from which many adult para- 

 sites appeared. The failure to produce adult parasites from the 

 eggs used in the above experiment is therefore not positive evi- 

 dence that this was due to infertility of the host eggs, ^^he experi- 

 ment shows however in a fairly conclusive manner that adult 

 females of the species of proctotrypid here considered will readily 

 parasitize infertile pentatomid eggs, and that the resulting larval 

 parasites will develop suffu initl v to cause the host eggs to take on 

 the characteristic .-oK.r ot para^itiznl fertile eggs. 



Farthniognu s,. ,nu/ it^ ,<l 'I »v to si x of offspring. No absolute 

 proof of paitlunoon.etH d(Nelopinent of the eggs of TiUmmus 

 ashrtyadi was obtained, but the (ontiilnitarv e\i<len(e from the 

 few breeding experiments undertaken furnishes a good basi.s for 

 the supposition that parthenogenetic development occurs and 



