320 



DESCRIPTION. 



The insect was originally described by Thomas Say in the 

 Boston Journal of Natural History, vol. I, page 268, 1835, as 

 Figites inipafiens, from specimens collected in Indiana. This 

 description is copied below for reference and is given in smaller 

 type so that those not specially interested may omit reading it. 



"F. Impatiens. — Black : mandibles and feet piceous. 



"Inhabits Indiana. 



"Body polished black : antennae piceous-black, two-thirds the length 

 of the body, wivh scattered hairs: beyond the sixth joint moniliforn: 

 terminal joint ovate conic: mandibles piceous, area of the stemmata a little- 

 elevated : behind which, on the occiput, are oblique impressed lines : 

 scutel with the margin depressed and rugose, the disk oval, the edge 

 obscurely piceous, with an indentation behind, within the edge : wings 

 hyaline : nervures yellowish : feet piceous. 



"Length three-twentieths of an inch.'' 



Any one who has first observed the males and females will not 

 confuse them again, as the antennae of the former are about 

 three times as long as those of the latter, this being the most con- 

 spicuous character. 



BEHAVIOR. 



The insect flies readily and also moves about in the dung with 

 perfect ease. The female is armed with an ovipositor nearly as 

 long as the entire insect. This organ is normally hidden in the 

 body and is withdrawn when eggs are laid. When extruded it 

 curves forward beneath the body and pierces through substances 

 while reaching out for its host within which one or more eggs are 

 deposited. Both larva and pupa of dung flies are attacked nor 

 is preference shown for any particular species of fly, provided it 

 is a dung inhabitant. The egg so laid hatches within the host 

 and the resultant grub feeds and grows at the expense of the host 

 substance surrounding it. It reaches maturity within the latter's 

 integument and when fully formed emerges through the aperture 

 made by gnawing off an end of the pupa. The fly larva even 

 w^hen parasitized attains the pupa state so that the parasite in- 

 variably issues from that state of the fly. The parasite is so large 

 wdien compared with the horn fly pupa that it was doubted at 

 first whether the latter would be subject to attack, but upon con- 

 finement with pupae of this fly it was observed to oviposit in them 

 and the parasite was subsequently brai from them. 



