General Characters, Life History, and Biology 

 of the Forms Studied 



1. Helophorinse 



Egg-case proper continuous with a distinctly hollow tube at the cap end. Many 

 eggs enclosed. Larva with the head nearly horizontal, slightly elevated; ocular 

 areas round, convex, and in groups of six, closely aggregated; antenna? with their 

 points of insertion nearer the externo-frontal angles than those of the mandibles; 

 antennal appendages of second segment two in number; epicranial suture absent; 

 labrum and elypeus reduced; mandibles stout, sharply pointed, and with distinct 

 inner teeth; labium and maxilla inserted at the anterior margin of the under side of 

 the head; maxilla palpiform; palpiger slightly dichotomous at the distal end; gula 

 reduced and distant from the occipital opening. Abdomen with nine complete seg- 

 ment?, each with tuberclar areas, the tenth distinct but reduced; cerci three-seg- 

 mented Holopneustic type of breathing with well-developed bifore spiracles. 



Helophorus Fabricius 



Often taken in company with the common Anccena and Paracymus, 

 these three genera are the most abundant in the Cayuga Lake basin. 

 All representatives of this genus may inhabit the same pool but more 

 frequently the different species seem to be segregated. It is difficult to 

 distinguish the various species in the field but, as a rule, H. lacustris 

 may be known by its usually larger size. In addition to it, H. linearis, 

 H. riridicollis (lineatus), and H. granulans, named in the order of their 

 abundance, are found here. Very little work has been done in this 

 country on the species. They are very close to each other in structure. 

 Distribution is limited, the representatives occurring only in the pale- 

 arctic, nearctic, and Central American regions. European authors have 

 worked extensively on the life histories of Helophorus and they are 

 listed in the table (page 5), but in America nothing has been done. 

 However, H. granulans, which Schiodte described, is holarctic. 



Egg-cases were taken out-doors in May and June. The cases 

 were formed in moss or alga near the bank with only the tubular filament 

 exposed, the egg-case proper being hidden completely. From six to ten 

 eggs were found in each of the cases. During tlie latter part of May sev- 

 eral larva? were taken, in company with Anccena larvse, from the under 

 side of a stick at the water's edge. While the larva? have been observed 

 eating entomostracans and various other animal tissue, it is worth re- 

 calling Perris' note that H. rugosus was observed in the stalk of Brassica 

 preying on a Psylliodes larva. 



17 



