90 Orthorrhajilia brachycera. 



tubercles, placed a little obliquely, oiie behiiid the other; above 

 the four transverse tubercles, just in front of the head, tliere are 

 two rathor large tubercles, and above these, somewhat behind the 

 antennal sheaths, and behind the transverc fracture, fornied by the 

 escape of the imago, there are two small ones. The four transverse 

 tubercles bear no brislles. but the others each bear a bristle with 

 exception of the two foremost in front of the head, which in Chrysops 

 (in contradistinction to Tahanus and Hcrniatopota) each bear two 

 bristles. 



The ovipositing of the American species C. aestuans v. d. Wulp, 

 moerens AValk. and caJUdus O. S. has been examined by Hart (Bull. 

 of the lUn. state Laborat. of nat. hi.st. IV, 1S!»5), and Hine (U. S. Departm. 

 of Agricult. Miscell. Papers, 1906. Techn. Ser. No. l!2. II). The eggs are 

 deposited on stalks and leaves of aqualic [ilants as oval masses of 

 about 10 mm. in length and 3 — 4 mm. in lireadth. with the eggs in 

 a single layer, in contradistinction lo the nianner followed by Tabanus. 

 Hine 1. c. gives an exellent description of the ovipositing of (/'. moerens, 

 which I shall quote: „The feniaie alights on the leaf with her head 

 downward and begins the process by pushing the tip of her abdomen 

 forward toward the under |iart of the thorax and placing the pro- 

 truding end of an egg against the leaf. The end sticks fast in con- 

 sequence of the glube-like substance which accompanies it, and she 

 then nioves the tip of hor abdomen back to its normal position, thus 

 freeing the egg. By similar movcments one or two eggs are placed 

 lo one side of the first, and two or three to the other side of it. The 

 unlinished end soon becomes V-shaped; she moves slowly forward 

 and lifts the tip of her abdomen lo one arm of the V and piaces eggs 

 along down until the apex is reached ; tlien changes to the other arm of 

 the V and piaces eggs along down to the apex on this side. It was 

 noted in specimens of this species observed that sonielimes a female 

 would place as many as three rows on one side, one after the other, 

 before changing lo the opposite side. It is only necessary lo study a 

 mass of these eggs in order to see the precision. in reference to one 

 another, with which the different specimens are arranged." The eggs 

 are shining black, but paler when just deposited. The ovipositing of 

 this species look place in July and August. The female was not 

 easily disturbed during the ovipositing. The incubalion period of this 

 species was rather short, only six days. The larvæ are said to live 

 in water. mud or damp localities: this certainly holds good with regard 

 to the Danish species, as I have seen pupæ of these found in the moist 

 sand at the borders of lakes (nifipes, quadratus, relictus). The eggs are 

 deposited in summer, the larvæ liibernates and the transformation to 



