326 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 



Fig. 63.— Hair-woems.— a, aBterior ex- 

 tremity of tlie female Variable Gordius ((?. 

 varius) ; h, the same of the male ; c, anterior 

 extremity of the Linear Gordius (O. line- 

 aris) ; d, side view of the posterior extrem- 

 ity of the male of the same species; e, an- 

 terior extremity of the Eobust Gordius (G. 

 robustus) from Kansas ; /, posterior extrem- 

 ity of the female of the game species, exhib- 

 iting the genital pore (after Leidy). 



tian animal {Herpestes ichneumon^ L.) that hunts for and feeds on croco- 

 dile eggs, it was also ai^plied, both by Pliny and Aristotle, to a wasp 

 that hunts spiders and caterpillars, for which reason Linnseus appropri- 

 ately used it to designate the parasitic family we have been consider- 

 ing. 



Hair-worms. — Of all the different enemies of our locust, these 



Z^;^ ^^"^ £^ ^^•'^ long, thread-like worms are the most 



liill Mm 1 r^™*l curious and remarkable. Occurring in 



"""I HH I h~ — m all parts of the world, and mentioned 



I llll ^ ^3 ^^^^ ^^ Aristotle, they are by no means 



PHI (r\ F~j^~tS rare. We have on several occasions ob- 



■^^'^:Mi \\ I /^-:^-~N tained specimens from spretus, and a 



number of our correspondents have re- 

 ported the locusts affected by them. 

 Mr. I. G. McGrue, of Audubon, IMinn., 

 even asserts that in that part of the 

 country the hair-worms destroyed as 

 many locusts, in 1875, as did any other 

 enemy. The locust infested with one 

 of these worms may be recognized by 

 its pale and sickly look, and especially 

 by the want of color on the hind thighs. The worms are not infrequently 

 found within the young and unfledged locusts, but far more often noticed 

 within or issuing from the winged individuals. Ordinarily there is but 

 one worm, but as many as five have been found, within a single locust. 

 If we carefully detach the head of a full-grown locust infested with one 

 of these parasites, just before it would naturally issue, we shall find the 

 coiled ends thereof protruding from the thorax, and the rest of the 

 animal coiled up longitudinally around the intestines and among the 

 viscera, the muscular, secretory, and reproductive organs of the locust 

 being much wasted, and the worm so closely pressed against or coiled 

 firound them as to almost comxjletely occupy the whole inside of the 

 poor locust, from the head to the anus, through which last the parasite 

 eventually issues. 



These hair-worms are not only very frequently found in different 

 locusts, grasshoppers, katydids, and crickets, but Professor Leidy even 

 has one from a cockroach. They Ukewise occur in many other insects 

 and smaller animals, as beetles, moths and butterflies, bees, two- winged 

 flies, spiders,- and snails.* As a rule, the worms forsake Lepidoptera 

 while these are in the larva state, or, more rarely, in the pupa state ; 

 whereas they generally issue from Coleoptera and Orthoptera only after 

 these have acquired the perfect state. They belong to two different 

 genera, Gordius and Mermis, differing more in internal structure than in 



82Siebold (Ent. Zeit., Stettin, ix, 1848, pp. 295-300; xi, 1850, pp. 332-336) gives a list of Articulates 

 found infested with hair-worms up to that time, from which it appears that insects of all Orders except 

 Iseuroptera ore attacked, while even mites are probably infested. 



