14 BULLETIN 66, UNITED STATES ' NATIONAL MUSEUM. 



The eggs mature within the body cavity, and the young (of which 

 the writer once counted 2,100 to one female) (Pierce, 1904), find 

 exit from the body of the parent through from three to five median 

 canals opening in the 2d to 4th, 5th, or 6th segments (such canals 

 are nowhere else found in Insecta, but occur in the Annelida). 

 They have passed into a larger passage formed between the venter 

 of the female and its uncast pupal skin, in which they pass forward 

 and find exit through a slit between the head and prothorax on the 

 cephalothorax. The female reposes with its venter upward, so 

 when the young come out they crawl all over the body of the host. 

 These young look like the primitive thysanuran Campodea, being 

 very lively little hexapods, with two bristles from the caudal end, and 

 with padded, clawless feet. The name given by Chobaut is tri- 

 ungulinid, because of the resemblance to the meloid triungulins. 



The triungulinid remains upon the body of the host until it gets a 

 chance to slip off or is brushed off into a nest or flower. In the latter 

 case it waits until another host comes along and takes passage with it, 

 and is carried to a nest finally. When it reaches a nest it hunts 

 around until it finds a larval host, into which it quickly burrows. 



Inside its host parasitic life quickly causes it to lose its legs, and the 

 eyes to disappear, and it is soon entirely grub like ; then the segments 

 of the head and thorax fuse. The male and female, after the second 

 molt, appear different, the female becoming as just described, while 

 the male becomes cylindrical and in the later stages shows a patch of 

 eyes, resembling the primitive collembolan eye patches but more 

 regular. The anterior portion hardens and is pushed outward, 

 resembling a dipteran pupa case, with tuberculate head and a little 

 cap at the tip of the cylinder. Within this skin a real pupa, like the 

 hymenopterous pupa, forms, and then another pupa forms within this, 

 and finally the adult develops inside of these three skins and emerges 

 by casting the cap from each skin. The adult male is a most peculiar 

 insect with one pair of large, milky white wings, shaped as a quadrant 

 of a circle; with a short transverse head; with large eyes on stalks, 

 composed of many separate hexagonal facets divided by hairy par- 

 titions; with antenna? branched and covered with delicate sense 

 organs; with rudimentary mouth parts, and with little paddle- 

 shaped balancers on the mesothorax. 



These insects fly like a flash, darting here and there, and with the 

 balancers vibrating in unison with the wings and making quite a 

 loud hum for such little creatures (for the largest known is but a 

 quarter of an inch long). Their sole purpose in life is to fertilize the 

 females, which act is accomplished by setting loose of the semina 

 either in the brood canal or oesophagus of the female. They five 

 but a few hours, five being the longest recorded, with one exception, 

 when Friese had a male Stylo fs live sixty-two hours (Friese, 1893). 



