58 AN INTRODUCTION TO ENTOMOLOGY. 



Sub-Order I. — COLLEMBOLA.* 



[Spring-tails^) 



To this sub-order belong certain minute insects which have re- 

 ceived the common name Spring-tails. They are often of micro- 

 scopic size. The majority live on decaying matter ; and are very 

 common under stones and decayed leaves and wood, in the chinks 

 and crevices of bark, among moss, and on herbage in damp places. 

 Sometimes they occur abundantly in winter on the surface of snow , 

 where they appear as minute black specks, which spring away on 

 either side from our feet as we walk. And some species collect in 

 great numbers on the surface of standing water. 



The body consists of the head, three thoracic and six abdominal 

 segments. The abdominal segments are not well marked in some 

 forms. No compound eyes exist in this sub-order. There is, how 

 ever, usually a group of simple eyes on each side of the head. The 

 antennae consist of but few, four to eight, segments. The mouth- 

 parts are formed for biting, except in Anoura, where the mandibles 

 and maxillae are wanting. 



The name Collembola refers to a curious organ situated on the 

 ventral aspect of the first abdominal seg- 

 ment, the ventral tube or sucker. " In 

 Podnra, Lipura, and the allied genera, this 

 organ is a simple tubercle ; divided into 

 two halves by a central slit ; in other 

 genera, as, for instance, in Orchesella and 

 Tomocems, the tubercle is enlarged, and 

 FlG ' ' ^tubbockT^ <After becomes a tube divided at the free end 



into two lobes. In the Smynthuridae and 

 Papiriidae the organ receives a still further and remarkable devel- 

 opment ; from the end of the tube the animal can project two 

 long, delicate tubes provided at their extremity with two glands." 

 (Lubbock.) By means of this sucker and the fluid excreted by its 

 glands these insects are enabled to cling to the lower surface of 

 smooth objects. 



The popular name Spring-tails was suggested for these insects 

 by a peculiar leaping apparatus which most of them possess. It 

 consists of a long appendage of either the fourth or fifth abdominal 

 segment, v/hich extends under the abdomen towards the head. 



* Collgmbola. colon {KooXov), a limb; cmbole (eufioXr/), a throwing. 



