124 Annals Entomological Society of America [Vol. XII, 



on the disc and several strong black bristles on its margin, femora black, 

 tibiae and tarsi dark red, apices of tibise and tarsi darker in some speci- 

 mens than others; wings hyaline, male costa slightly dilated. Male 

 abdomen, first four segments gray on the sides and narrow hind margin; 

 segments five, six and seven silvery, hypopygium black and largely 

 black hairy. Female abdomen with each segment gray on sides and 

 narrow posterior border, oviduct nearly as long as the last four abdominal 

 segments. 



From Slidell, Louisiana, and from Florida. 



Much like cestuans and there is some doubt in regard to its 

 distinctness from that species, but the large size and robust 

 form give it quite a different appearance. The specimens I 

 collected at Slidell, Louisiana, were taken from the trunks of 

 trees. 



Erax aestuans Linne. 



Variable in size. Usually ranging from 18 to 22 millimeters, but 

 specimens as small as 14 millimeters and others as large as 28 are taken 

 occasionally, especially females if measurement is taken to the tip of the 

 oviduct. 



The body usually is more hairy than in other species of its group. 

 Mystax composed of black bristles and gray hairs, dorsum of the 

 thorax with numerous black hairs and bristles on the posterior part, 

 scutellum with an apical row from six to ten black bristles, wings 

 slightly tinged with brownish, legs black with bases of tibia rather dark 

 brown, abdomen black with a narrow gray posterior border to each 

 segment. The male has from two to four apical abdominal segments 

 silvery. Figure 17 shows the form of hypopygium from lateral view. 

 The oviduct is slender, nearly as long as the last four abdominal segments 

 and usually turned to one side or the other in dry specimens. Figure 4. 



Habitat: Widely distributed over north-eastern North 

 America, ranging to Florida, New Mexico and Wyoming. A 

 very abundant species over much of its range. 



The rather pronounced hairiness of the body, especially the 

 posterior part of the dorsum of the thorax where the hairs are 

 unusually long and plentiful, the row of bristles on the scu- 

 tellum, the brown and not yellow tibiae and form of hypopygium 

 rather easily distinguishes this species from others of its group. 



Variation in size and the extent of the silvery color of the 

 male abdomen has given an excuse for a number of synonyms 

 of the species. Thus macrolabis is used for the specimens 

 having four segments silvery. I have observed this character 

 often and find it appearing so irregularly that it can hardly be 



