162 



SIXTH ANNUAL REPORT 



[Fig. 48] 



NATURAL ENEMIES . 



Crows and blackbirds are 

 known to devour the perfect in- 

 sects, but one would suppose that 

 the hard-shelled eggs would re- 

 main entirely unmolested by pre- 

 daceous animals. Yet I once found 

 two of these eggs in the stomach 

 of a Baltimore Oriole, associated 

 with the elytram of some beetle, 

 the AYings of a was]^ (Trypoxylon) 

 and many seeds. They are also 

 quite often infested by a curious 

 little Chalcid-fly — the Atiiiffaster 

 mirahilis Walsh — which may be 

 popularly called the Back-rolling 

 Wonder. This little fly was very 

 fully described, both generically 

 and specifically, in a posthumous 



Antigaster MiRABiLis: — a, female, Avinss expaudeil, ^„^„„ „j? -i\/r„ ■\xr„i„U7^ r A^-,^^,'^^ 

 nat. size indicatod underneath; 6, .Slime, siUe view paper Ol Mr. Walsh's {American 



partly rolled up; c, same uearly rolled up; f/, un- j^ . j jTT .^^ vac 0'7A^ 



teuiia of same. JbntomologisU H-, PP- ^68-370). 



Mr. Walsh had captured three females at Rock Island, Ills., but 

 neither the male nor the habits of the species were known until I 

 bred specimens from the eggs of our Angular-winged Katydid. I 

 have bred it from such eggs received from Kansas, several parts of 

 Missouri, and from Chattanooga, Tenn.; also from the eggs of a large 

 Sphinx moth found on Willow ; so that it is quite wide-spread, and 

 not strictly confined to Katydid eggs. 



The anomalous nature of this little fly consists in the habit pos- 

 sessed by the female (Fig. 48, «, J, c) of rolling up into a ball back- 

 ward, and in the very great dissimilarity of the male (Fig. 49, c). 

 Many other insects roll up downward, with a convex back, while 

 [^''.-- '''1 some few, as the Rove-beetles, 



{Staphylinidce), curl up more 

 or less backward when dis- 

 turbed; but no other species is 

 so curiously constructed for 

 rolling backward into a per- 

 fect ball, unless it be some be- 

 longing to the very closely al- 

 lied genus Eupelmus. 



I shall append in a foot- 



maiffly^''rf! toant'eumu^^^^^^^ veutial view; ., ^^^^^ ^^^ ^^^ benefit of the SCi- 



ANTIGASTKR MIRABILIS :- 



: of ISIicrocentrus fivim 



