l82 



THE AMERICAN ENTOMOLOGIST. 



Gyrinus Larva : Terrestrial Insects in Sto- 

 mach of Shad.— I have sent you to-day two 

 packages, one containing a larva of Gyrinus, an 

 aquatic Coleopter, the other containing terres- 

 trial insects. The latter are from a mass com- 

 prising many species of minute insects (C/mlcids, 

 Jassiis, Tifltleps iiisidiosiis, and several Diptc-ra), 

 found in the stomach of a small Ohio shad, I 

 took the stomach out myself and examined it 

 immediately, or one might imagine that a mis- 

 take had been made. There was not a trace of 

 any aquatic creature in the stomach. — S. A. F. 



The Coleopterous larva is evidently that of 

 some Gyrinid and probably of the genus Gyrinus. 

 All that we know about the larvse of this genus 

 is based pretty much upon what Modeer wrote 

 about a century ago, and according to that author 

 these larvae are distinguished from all other 

 aquatic Cokoptera by having a series of lateral, 

 ciliated, abdominal filaments, which yet show on 

 the partially macerated abdomen of your speci- 

 men. Your larva differs from the description in 

 the mandibles being toothed, but it is not at all 

 uncommon with Coleoptera for the young larva 

 to have toothed mandibles, the teeth being sub- 

 sequently lost as full growth is acquired. In the 

 smaller vials. No. I is a Typhlocyba which may 

 be a form of vitis. The species in this genus are 

 extremely variable, and it is doubtful whether 

 vitis Harris is anything more than hasilaris Say. 

 No. 2 is a little Mtiscid, the wings of which are 

 so crumpled that the genus cannot be determined. 

 It looks very much like an undescribed species 

 which we have reared from a larva mining the 

 leaves of Vt-rbaia. No. 3 is an interesting Eii- 

 rytomid, a sub-family of the C/iahidid,€, and ap- 

 proaches Isosoma. Without the other sex, gen- 

 eric determination is hardly to be ventured on, 

 and as to the species, these minute creatures 

 have been so little studied in this country that 

 the one in question is in all probability new. 



Descriptive Department. 



FURTHER REMARKS ON THE DIFFERENCES 

 BETWEEN PRONUBA AND PRODOXUS. 



BV C. V. RILEV. 



In our original reference to the Bogus Yucca 

 moth, as quoted on p. 143, we stated that the 

 female differed from Prontiba yitccasella not only 

 in lacking the maxillary tentacles, but in the ovi- 

 positors being "of different shape and faintly 

 notched superiorly," the statement having been 

 made upon examination with an ordinary lens of 

 the specimens borrowed from Dr.Hagen. As none 

 of the specimens which we had subsequently ob- 

 tained had the ovipositor extruded, we could not 

 very well verify, under the microscope, our pre- 

 vious description of the ovipositor, and were 



led to the opinion that the notched character 

 might be due to a varying degree of contraction 

 in the dry specimens, and further that the ovi- 

 positor oi Prodoxus was probably not exsertile. 



Having recently found in Washington, D. C, 

 the Prodoxus more abundant even than Pronuba, 

 we have been able to make a more careful study 

 of the ovipositor and we find that, as in the other 

 structural characters, the differences between the 

 ovipositors of the two are striking and important. 

 In Pronuba, when the ovipositor is entirely 

 withdrawn, the tip of the abdomen presents a 

 truncate appearance, the terminal joint being 

 bluntly rounded at tip, with a slight projection 

 both above and below, and a corrugated ridge 

 doj-sally a little in advance of the tip. This ter- 

 minal joint is very much compressed from the 

 sides, with a few stifl!" hairs around the terminal 

 borders. The ovipositor issues from the middle 

 of the truncate end, is very fine, tubular, the 

 basal joint beautifully imbricato-granulate, the 

 terminal joint perfectly smooth, long and pe- 

 culiarly constructed at tip, the extreme tip being 

 notched or serrate, and a dorsal membrane, also 

 finely and sharply serrate, running anteriorly from 

 it — the whole recalling in form the caudal and 

 second dorsal fins of the Lamprey {Petromyzon). 

 Ventrally along the terminal joint is seen a 

 membranous duct, which broadens just in front 

 of the tip, and has an outlet from which a soft 

 and extensile oviduct can be extruded. The 

 whole structure is, in fact, admirably adapted to 

 cleaving through the fruit of the Yucca and then 

 running into the ovarian cavity. 



The tip of the abdomen \x\Prodoxus\% not trun- 

 cate as in Pronuba, but pointed and slightly beveled 

 off" superiorly. The terminal joint is not com- 

 pressed but quite considerably swollen, the ovi- 

 positor issues from the beveled dorsal portion of it, 

 is dark brown, laterally flattened, between three 

 and four times as broad as in Pronuba, shorter ; the 

 basal joint with a closer, finer ribbed sculpture, the 

 terminal joint with the end obliquely cut off be- 

 low and having a series of minute teeth, the ven- 

 tral one being more conspicuously produced. 

 It has, also, a series of 8 or 9 more prominent, 

 broad teeth along the dorsal edge, while two dis- 

 tinct grooves run along the whole length and sev- 

 eral smaller ones are noticeable near the tip. 

 The ventral membranous duct is less conspicu- 

 ous and has its outlet just forward of the ventral 

 notch at tip. 



It requires but little practice to at once distin- 

 guish the females by an examination of the tip of 

 the abdomen with an ordinary lens, even il the 

 ovipositor is not extruded ; the heavier, more 

 swollen, dark brown and more pointed terminal 

 joint of Prodoxus being quite unlike the com- 

 pressed, ordinarily honey-yeilow, more attenuate 

 but truncate terminal joint oi Pronuba. 



