SHORT CHARACTERS OF THE ORDERS 

 OF INSECTS 



This table is not meant to be learnt by heart, but to be 

 used for reference. The large orders which will almost 

 exclusively engage the attention of the beginner, are in 

 dicated by capital letters. 



Section I. Ametabolic — i.e. without transformation ; never 

 acquiring wings, and undergoing no change of form ; there 

 is no resting-stage. 



Order Thysamtra (bristle-tails). The abdomen consists of 

 ten segments. A pair of long antenna-like organs project 

 from the hinder end of the body ; in one genus these are 

 replaced by a forceps. A number of the abdominal segments 

 bear small appendages. 



Order Colkmbola (spring-tails). The abdomen consists of 

 not more than six segments, the first of which bears a ventral 

 tube or papilla. In many there is a forked spring upon 

 the hinder end of the abdomen, which can be bent beneath 

 the body, and usually secured by a catch. When the pro- 

 jections are released, they throw the insect into the air. 



Section II. Hemimetabolic — i.e. undergoing incomplete 

 transformation. With very rare exceptions (male Coccidse, 

 and some Thysanoptera) there is no resting-stage. The wing- 

 rudiments appear externally upon the larval thorax, and enlarge 

 gradually at successive moults. 



Order Ephemeridce (May-flies). Mouth-parts vestigial in 

 adult. There are two pairs of membranous wings with reticu- 

 late venation, not much folded; the hind pair smaller or wanting. 

 The body ends behind in 2-3 tail-filaments. Larva aquatic. 



Order Odonata (dragon-flies). Mouth-parts biting. Antennae 

 short. There are two pairs of membranous, equal, and finely 

 reticulate wings, not folded. Larva aquatic. 



Order Plecoptera (stone-flies). Mouth-parts biting, but not 

 18S 



