416 THE STUDY OF INSECTS. 



being left to poison the atmosphere, is transformed into 

 myriads of living beings, whose swift flight and delicate 

 forms lend life and beauty to the landscape. 



SYNOPSIS OF THE DIPTERA. 



THE STRAIGHT- SEAMED FLIES. Flies in which the pupa escapes 

 from the larval skin through a T-shaped opening, which is 



formed by a lengthwise split on the 



back near the head end and a crosswise 

 split at the front end of this (Fig. 484),. 

 or rarely through a crosswise split be- 

 tween the seventh and eighth abdominal segments, adults without 

 a frontal lunule.* Suborder ORTHORRHAPHA (Or-thor'rha-pha). 

 The Long-horned Orthorrhapha or Nematocera (Nem-a-toc'e-ra). 

 Flies with four- or five-jointed pendulous palpi and with many- 

 jointed antennae, which are usually long. The segments of the 

 antennae, except the basal two, are similar in form, and are more 

 than six in number; they are often fringed with hairs or 

 bristles. f 



* The frontal lunule is a small crescent-shaped piece immediately above 

 the antennae, which is characteristic of the second suborder, the Cyclor- 

 rhapha. In most of the members of this suborder there 

 is a suture separating the lunule from that part of the head 

 above it, the frontal suture', and frequently this suture 

 extends down on each side to near the mouth (Fig. 485). 

 But as the suture is wanting in several families of the 

 Cyclorrhapha, it is often difficult to determine whether 

 the lunule is present or not. The following statement 

 will enable the student to recognize nearly all of the 

 members of the first suborder. ^sh'owfng ~f "mat 



The suborder Orthorrhapha includes : suture 



All flies in which the antennae are more than three-jointed, not counting 

 a bristle or style borne by the third segment. 



All flies with three-jointed antennae in which vein III is four-branched. 



Such of the flies in which vein VII 2 appears like a cross-vein, or curves 

 back towards the base of the wing, as lack the suture above the antennae. 

 This section includes only a few Empididae and the families Dolichopodidse and 

 Lonchopteridae. Nearly all of the flies in which vein VII 2 is of the form 

 described here possess the suture above the antennas, and hence belong to 

 the Cyclorrhapha. 



f The two types of antennae characteristic of the Nematocera and 

 Brachycera respectively are connected by intermediate forms. These 



