69 GENUS SCHISTOCERCA, STAL.
TABLE FOR SEPARATING THE SPECIES.
A. Antenna? of male nearly or quite one-half longer than head and pronotnui together. The latter angulate l)ehlnd. Lower edge of sides of pronotum and costal edge of tegniina light yellow-testaceous. " tlavotiijsciata DeGeer.
AA. Antenna' of male about one-fourth longer than the head and pronotum together. The latter more or Jess distinctly rounded behind, b. Anterior lobe of pronotum nari'ower than the head exclusive of the eyes, the posterior lobe abruptly expanded. paraiiensis Buna.
bb. Anterior lobe of pronotum not narrower than the head exclusive of the eyes, the posterior lobe gradually' and regularly expanding behind, c. Markings on apical half of tegmina composed of longitudinal streaks l)y the more or less interrupted infuscation of the longitudinal veins. pallens Thunl).
cc. Markings on apical half of tegmina composed of fuscous spots arranged in ol>liquely transverse series. cancellata Serv. Fig. 31. — ScJiistocerca paranensis — a dwarfed female specimen. S. florofitschifd DeGeer. Throughout the valley of the Rio Parana, but nowhere numerous.
*S'. jjaroiiensis Burm. The destructive locust of the countr\^ and represented in all the collections.
S. pdlleus Thunb. Several specimens of this more northern locust were observed along- the upper Parana between Corrientes and Formosa.
S. vam-ellafa Serv. Buenos Air(>s, Rosario, Santa Fe, Carcarana, etc. Quite a number of sp(>cimens of this species were examined during the writer's sojourn in the country. As will be seen by an examination of the accompanying illustrations, there is quite a resemblance in the general a])pearance of this and the p(ir(nie)isis imagos; but the saltonas are C[uite different. The viotcelldid som'^tiuies accompanies the
70 parajiensis in its flights. It is more at home on the west coast than east of the Andes.
Hg. SI. — Sehif>t'>cei ca paranensis Bunii. Fig. 33. — Schistocerca cancellata Serv. GENUS ATRACHELACRTS, GIGLIO-TOS.
A. unlcolor Gigho-Tos. A very common insect on the open camp from Buenos Aires northward to Paraguay where it has been known to increase to such an extent as to become a pest. Specimens were contained in all the collections examined. Cordoba (P. Schulz, H. Stempelmann ) ; Carcarana, (O. Thomas).
71 The accompanying- illustration will give the reader an idea of its general appearance. As its name implies it is of a uniform grass-green color.
Fig. 34. — Atrachelacriii unicolor (iiylio-Tos. — female. Fig. 3"i. — A. tniicolor. lualc, and ti]) of ahdomeii. GENUS DICHROPLUS, STAL.
The insects which comprise this extensive genus are very closely related to one another in their general appearance, and the few forms that have thus far been noted by entomologists have been so briefly described that it is a little doubtful as to their identity. This is especially true when the student is limited in the material that is accessible for study. However this may be, the writer, after considerable study, has separated them into IB species for Aregntina. Several of these occur in large numbers upon portions of the pampa region, and sometimes cause much injury to the grasses. They go by the general name of "tucuras, " which w^ord I jDresume simply means "grasshoppers." TABLE FOR SEPAKATIN'i THE SPECIES.
A. Female with the valves of the ovipositor emargiintely truiicato. Interval between the mesosternal lobes considerably longer tlian witle. Male eerci moderately long, compressed back of middle, beyond gently bowed, b Prosternal tubercle large, transverse. Lower edge and inner face of hind femora blood-red. General color dull brown. ob.sfuru Hrnncr.
bl). Prosternal tubercle not large, conical. Lower t-dge and inner face of hind femora yellowish, c. Smaller. General color olivaceous-yellow. Upper valves of ovipositor much longer than the lower ones. clieiis Stal. cc. Larger. General color brownish-yellow. Upper valves of ovi 1 ( ; or but little longer than lower ones. leiuniscatus Slab
72 AA Female with the valves of the ovipositor entire at apex, acuminate or snbaenminate. Interval between the mesosternal lobes usually. Imt not always, as broad or a little broader than long. b. Hind tibia' with nine spines in outer row. Tegmina and wings usually reaching or surpassing the tip of abdomen, c. Interval between the mesosternal lobes a little longer than wide. Upper edge of sides of pronotum generally dusky throughout, but sometimes only to the posterior sulcus, d. Tegmina not surpassing the tip of hind femora, e. Frontal costa suleate.
f. Posterior coxa^ marked externally with a dark line. g. Disk of tegmina dark veined. fuscil.s Thunb. gg. Disk of tegmina not dark veined. Lower sulcus and inner face of hind femora red. cinereii.s Bruner. ff. Posterior coxa^ not marked e.Kternally with a dark line. Tegmina sordid yellow, unieolorous.
bicoloi' Giglio-Tos.
ee. Frontal costa not suleate. Dorsal edge of tegmina ])aleveined. patruelis Stal.
d'l. Tegmina surpassing the tip of hind femora. e. Male cerci rather heavj' and straight. Lower sulcus of hind femora yellowish. " praten.si.s Bruner.
ee. Male cerci slender, incurved laeyond the middle. Lower sulcus of hind femora orange-red.
f. Smaller, very slender; the sides of pronotum jDarallel. Dusky band on side of pronotum extending to metapleur'a. exilis Giglio-Tos.
ff. Larger, less graceful: the sides of pronotum diverging posteriorly. Dusky band on side of pronotum continued upon tegmina to the apex. eloiig-a lis Giglio-Tos. cc. Interval between mesosternal lobes ful,ly as wide or wider than long. The dusky band on sides of pronotum more or less interrupted.
d. Posterior lobe of pronotum somewhat ascending posteriori}', a little longer than the anterior lol:)e. arrog-ans Stal. (h\. Posterior lobe of pronotum not ascending posteriorly, about equaling or a tritie shorter than the anterior lobe. e. Posterior coxa' fuscous or black spotted. Last ventral segment of male abdomen with the lateral margins black, f. Smaller. Himl tibia- red. punctulatus Thunb. ff. Larger. Hind tibia' greenish-testaceous. coii.spersii.s Bruner.
ee. Posterior coxa unspotted. Last ventral segment of male abdomenwith the margins never black, f. Dull olivaceous-yellow. Tegmina about reaching tip of hind femora, unieolorous: the latter with inner face and lower sulcus bright carmine, hind tibia olivaceous. Bergii Stal.
ff. Yellowish varied above with brown. Tegmina about onehalf as long as abdomen, brown, with a discal row of black dots and latero dorsal yellow lines continous with those on margins of disk of pronotum. Posterior femora internally on basal half carmine, lower sulcus yellow; hind tibia glaucous-green. vittatii.s Bruner. bb. Hind tibia' with eight spines in outer I'ow. Tegmina and wings abbreviated, about as long as ihe head and pronotum combined. Olivaceous-green. Postei'ior tibia> glaucous. aiiioenus Stal.
73 Dicliropli!^ ohsci/riis n. sp.
A moderately large and robust species, with the valves of the ovipositor of female emarginately truncate at apex and the interspace between the mesosternal lobes longer than wide. Lower sulcus of hind femora bright blood-red; hind tibiae purplish, somewhat infu seated near the base. General color dull brown ; tegmina mottled with rather large black dots throughout discal field ; venter yellow. Frontal costa wide with the margins blunt, sulcate in vicinity of ocellus : pronotum with the median carina heavy, conspicuous throughout; sides but gently divergent posteriorly, the last transverse sulcus about the middle. Tegmina rather narrow, reaching a trifle beyond the tip of hind femora but not quite to tip of abdomen. Posterior femora heavy at base, not reaching apex of abdomen. Prosternal sj^ine robust, long, and directed posteriorly so as to touch the front edge of mesosternum beyond the point of which it extends a trifle. Length f of body, female, 33 mm, of pronotum 7 mm, of tegmina '2'2 mm, of hind femora IH mm.
A single specimen collected during the month of January on the open camp near Carcarana (A. Kurriger). v. c/ieiis Stal. This insect has not been recognized among the various formes studied, but is included here because of its recorded Uruguayan habitat. Monte Video, Uruguay (Stal). I). lenniixcdfiis Stal. Not recognized by the writer, but reported as coming from Buenos Aires (Stal). />. jHiffiK'/is Stal. Buenos Aires (Stal): Resistencia, Cliaco (Giglio-Tos).
1'. bico/or Giglio-Tos. San Lorenza, Juju.y (Giglio-Tos). /.'. fu-scKs Thunb. Specimens from the Province of Santa Fe are referred to this species (O. Thomas). I>icli i'(>iihis cine reus n. sp.
General color dull cinereous vai'ied with brown and testaceous. Head in femah^ rather large, in male small: eyes quite large and protruding; fastigium of the vertex of male narrower than the diameter of second joint of antenna, in
74 the female about half again as broad; frontal costa of equal width throughout, sulcate in male from fastigium to clypeus, in female from ocellus downward. Pronotum, (male) with the sides nearly parallel, (female) somewhat expanding posteriorly, with a rather well defined broad brown band running from back edge of eyes along upper lateral edges of pronotum to base of tegmina, below this the sides are yellowish white. The transv^erse sulci quite plain, the posterior one a little back of middle; hind edge angulate. Tegmina and wings not quite reaching tip of abdomen in both sexes. General color of former light gray with inf uscation at base. Tegmina rather narrow toward the apex. Poterior femora with indication of two oblique dusky bands on outer face and upper edge, inner side, and also lower sulcus more or less tinged with bright orange red ; knees inside and out dusky, with the lower edges blue ; posterior tibiae with exception of a rather broad pale annulus near base blue ; base of wings yellowish, the apex dusky, the upper face black or dark brown.
Length : of body, d 17 mm, ? 26 mm ; of pronotum, d^ 3.5 mm, 9 5.75 mm; of tegmina, cf 10.5 mm, ? 16 mm; of hind femora, (^ 10 mm, 9 14 mm.
This insect occurs on the slopes west of the city of Mendoza, where it was found in small numbers upon a leafless, rather tall composite growing in the dry sandy bed of a creek. DichropluH pratejisis n. si3.
General color flavo-tetaceous varied with brown and black ; pronotum with light bands at edges of disk ; hind tibiae bluish-gray ; lower sulcus and inner face of posterior femora varying from yellow to dull orange. Interval between mesosternal lobes a little longer than wide. Tegmina a trifle surpassing tip of hind femora. Pronotum with sides gently diverging posteriorly ; the median carina of equal prominence throughout, cut near the middle by last transverse sulcus. The sides of head, back of eyes and pronotum to the last transverse incision dusky, in some specimens back of this con-
75 tinued as a ferruginous patch to hind edge of pronotum. Tegmina with the dorsal edges light veined, a few dusky spots above ; the disk more or less mottled with black, as is also the costal field, though to a much less degree. Posterior femora very heavy, with a basal, middle, and preapical dusky i^atch above; knees black both inside and outside. Cerci of male rather heavy, straight, and somew^hat spatulate apically. Last ventral segment of male abdomen obtusely conical. Prosternal spine hort, conical, obtuse. Length : of body, d^ 23-26 mm, ? 28 mm ; of pronotum, c? 5 mm, 9 6 mm; of tegmina, c? 1^^ mm, 9 18-22 mm; of hind femora, 13 S" mm, 9 14-16 mm.
This insect is quite robust and reminds one not a little of the common North American Jle/otoiihis hirittofKs in its general ajDjDearance. It occurs quite abundantly on the open camp in the provinces of Santa Pe and Buenos Aires where vegetation is rank. It has been reported as sometimes doingconsiderable damage to the grasses. (Collections of O. Thomas and A. Kurriger).
Fig. 8(5. — Diclbioijiaaarrogans, male, aud tip of abdomen.
Fig. 37. — Dichroplus pratensis^ male, and tip of abdomen.
D. exi/is Giglio-Tos. San Lorenzo, Jujuy, Resistencia, Chaco (Giglio-Tos).
D. elonr/atiffi Giglio-Tos. Province of Tucuman (Giglio- Tos) ; Cordoba (P. Schulz, H. Stempelmann) ; Carcarana, Santa Fe (O. Thomas) ; Rosario (A. Kurriger). This insect is one of the most abundant and widely dispersed species of the genus in middle Argentina.
70 D. arrogant St&l. Buenos Aires, Monte Video (C. Stal); LaColina, Buenos Aires and Bahia Blanca (Bruner). This insect was reported as a common destructive species in portions of the provinces of Buenos Aires and Bahia Blanca; and possibly also from Rio Negro and Pampa Central where rather small "tucuras" frequently destroy the "camp."
I). puHctulatui^ Thunb. This seems to be the smallest, most variable and at the same time most widely distributed species of the genus. Specimens were examined from all parts of the Republic north of the Rio Negro of Patagonia. Fig m. — Dichropln^ I Fig. AO.—Dichrop In s honqatus. male, and tip Fig. 3!).-Z>. j^i^^'C- p >' nctulatus, mala, of abdomen. tulatns. tVmale. and tip of abdomen. Fig. il.—Dichroplus coaspersus, female. Fig. 42.— D. arroga7is, female Dichroplus conspersus n. sp.
A moderately small but very robust species, of a duskv color, in which the hind tibiae are greenish yellow, the lower sulci and inner basal half of posterior femora bright red, and the interspace between the mesoternal lobes a little wider than long.
Head small ; pronotum greatly expanding posteriorly, the median carina obliterated on middle lobes, moderately plain on anterior and posterior lobes, severed by all three transverse sulci, the last a little in advance of the middle ; the posterior lobe a little the longest, right-angled in male, a