THE CRANE-FLIES OF NEW YORK PART II 821 



a heavy fringe of Cladophora and other algae just below the water line, with a film of " skin 

 algae " extending a little higher. 



All over the sides of the plank, in either sun or shade, the adult simulans could be seen 

 throughout the summer months, sometimes in considerable numbers. I was first attracted 

 to notice them by their habit of running rapidly sidewise along the pier, and their resemblance 

 to harvestmen (Phalangidae). They run habitually sidewise, apparently rarely moving 

 forward except to escape an obstruction, and very rarely appearing on the top of the pier. 

 They rest in an inverted position on the under surface of the overhanging plank on the top 

 of the pier. They stiok to the surface so persistently that it is difficult to make one take 

 flight; they may be driven all about on the surface, or poked with a stick; they can fly well 

 enough when they will, but when induced to fiy they settle again almost at once, and within 

 a few feet of their starting place. 



They are associated upon the piers with Geranomyia canadensis and with numerous 

 midges and micro-caddis flies (Hydroptilidae) and a few larger caddis flies of the genus 

 Hydropsyche. 



Males are more in evidence, but probably not more abundant in fact. The females come 

 out from their resting places only to lay their eggs, and are only to be seen when busily engaged 

 in the performance of this task. They stand on tiptoe, with the long ovipositor held in 

 vertical position at the tip of the deflexed abdomen, and they swing the body up and down 

 in rapid shuttlelike vibration, freely rising and falling on the long and widely outspread 

 legs. Thus the point of the ovipositor is driven against the wet surface of the plank, thrusting 

 almost as rapidly as the needlebar of a sewing machine; it is moved about over the surface, 

 as if searching for soft spots in the wood, and occasionally it makes a deeper thrust when a 

 suitable place is found, and an egg is deposited. 



The egg-laying process is often interrupted and is continuously interfered with by the 

 too importunate males. When a male in running about on the plank comes upon a female 

 ovipositing, he stands directly above her at the full upward stretch of his legs, while she 

 goes right along with her work; but the instant she ceases her vibrating and lifts her ovi- 

 positor, he is ready with his forceps, upturned and outspread at the tip of his decurved abdo- 

 men, to seize her. Usually she does not want to be interrupted and moves away, while he 

 tries to run parallel and maintain all the while his position of vantage above her. Often 

 other males are encountered, and then the males engage in a rough and tumble fight. They 

 push and shove each other in a most ludicrous manner, reminding one of pigs fighting, 

 and often an encounter of this sort enables the female to escape and go on quietly with 

 her work. 



The males have well developed eyes, but their sight must be very poor; for, while always 

 searching for females, they seem quite unable to find them by sight, often passing females 

 at work within a distance of a few centimeters. But their tactile sense seems more acute, 

 When a male in running to and fro had passed several times within six centimeters of a 

 female without noticing her, was deflected from his course toward her by an obstruction 

 I purposely placed in his way, he instantly sprang toward her upon the slightest contact, 

 even of tips of tarsi, but was quite unheeding until this contact occurred. If it did not occur 

 he would pass on, even by the narrowest margin. 



All stages are found together on the piers. The eggs are laid in the soft spots in the old 

 wood, where the surface of the pier is kept wet, but not continually covered by water, in 

 the zone of the " skin algae." The larvae live exposed or thinly algae covered, and crawl 

 about slowly over the wet surface. They are greenish in color and very inconspicuous. 

 In a cavity among the stems of the dwarf mosses (Bryum binum Schoeb. var. varium Lindb. 

 and Amblystegium orthocladon Lesq. and James) in a crevice at the upper limit of the 

 wet area the larva spins about itself a sheet of tissue and fastens bits of moss stems and 

 leaves to its outside, and transforms inside the tube thus formed into a pupa. The tube 

 is longer than its body, and the pupa moves in or out at will, doubtless by the aid of the 

 hooks at the ends of its body. 



