accessory glands of the head, or by the same secretion together with 

 secretion of the pedal glands. When the outline of the tube is complete, the 

 larva strengthens it inside, adding to the thickness of the walls; it turns 

 forward and backward, upward and downward inside the case during the 

 weaving (Figure 12l). A well-fed larva spends about one hour in search of 

 a location for the tube when the speed of the current is 0.04 — 0.07 m/ sec; 

 it needs about 6 hours for the weaving of the tube; the case is usually built 

 in the evening, night or early morning, between 5 p. m. and 5 a. m. After 

 completion of the dwelling tube the larva rests for several hours. 



FIGURES 119—121. Construction of a net by the larva of Neureclip- 

 sis bimaculata (after Brickenstein): 



119 —diagram of the capturing funnel, A — straight, B —coiled, C — coiled 

 twice; 120 — spinning a silk thread; 121 —the larva turns about and cleans 

 itself. 



The weaving of the capturing funnel consists of a complicated series of 

 movements for the drawing of the longitudinal threads (dark larva in 

 Figure 122) and for their interweaving with the transverse threads (light 

 larva in Figure 122). After completing the skeleton of the thin-walled, 

 coarse-meshed, funnel-shaped net, the larva thickens the walls of the 

 chamber, adding new layers of threads on top of each other to the inner 

 side; during this process the larva changes the initial, relatively simple 

 funnel; it increases its breadth in some places, and narrows it in other 

 places, forming curves and convexities; Figure 123 illustrates the inter- 

 mediate stage of the weaving of the funnel and a completed net of over 

 20 cm length. 



74 



