The Simplest Insects 



63 



attached to the next to last body segment or to the antepenultimate one. 

 It consists of a basal part and of two terminal processes. 

 It is carried bent forward under the body, with the bipartite 

 tip held in a little catch on the third abdominal segment. 

 In some species the catch is lacking. The springtails also 

 possess a curious organ on the ventral aspect of the first 

 abdominal segment which appears to be a small projecting 

 sucker or tube. This sucker is often more or less divided 

 into two parts, in one family consisting plainly of two 

 elongate, delicate tubes (Figs. 96 and 97). The use of 

 this peculiar structure has not been definitely determined. 

 Some entomologists think that it serves as a clinging organ, 

 enabling the insect to attach its body firmly to the object 

 upon which it rests. Others believe that the sucker serves 

 in some way to take up moisture, while still others be- 

 lieve it to aid in respiration. The Collembola as well 

 as the Thysanura cannot live in a dry atmosphere. 

 This suborder is divided into five families, as follows 

 (MacGillivray) : 



A. Spring wanting .^phorurid.e. 



A\. Spring present. 



B. Spring arising from ventral side of 

 antepenultimate abdominal segment. 

 P0DURID.E. 

 BB. Spring arising from ventral side of penultimate abdom- 

 inal segment. 

 C. .\bdomen elongate, cylindrical, much longer than 



broad ENTOMOBRYID.E. 



CC. Abdomen globular, but little larger than broad. 



D. Terminal segment of antenna; long, ringed. 



Smynthurid.c 



DD. Terminal segment of the antenna: short, with 



a whorl of hairs Papiriid*. 



Fio. 95. — Machi- 

 lis sp., from Cali- 

 fornia. (Three 

 times natural 

 size.) 



Fig. 96. — The spotted 

 springtail, Papirius 

 maculosus,vi\t\i spring 

 folded underneath 

 body. (Natural 

 length, 2 mm.) 



Of these five families the members of one, the Aphorurida?, in which 

 the spring is wanting, are non-saltatorial. In all of 

 the others leaping is a characteristic habit. The 

 Smynthurida; and the Papiriida; are represented by 

 but one genus each, viz., Smynthurus and Papirius. 

 Smynthnrus hortensis is a common form in gardens, 

 and may be called the "garden-flea." It is found 

 in the Eastern States in May and June "upon the Fig. 97.— The spotted 

 leaves of young cabbage, turnip, cucumber, and ^ttlj; fp^girndrd: 

 various other plants, and also on the ground. It (Natural length, 2 mm.) 



