568 



AN INTRODUCTION TO ENTOMOLOGY 



Ganonema americdna. — The larvae were found abundant in alder- 

 bordered streams. The cases made by this species differ greatly 

 from those of other described American caddice- 

 worms. The case is made of a single piece of wood 

 or bark or a twig ; this is hollowed from end to end, 

 and lined with silk. Although common, they are 

 most inconspicuous among the debris on the bottom 

 of the stream. Figure 699 represents a case with the 

 silk tube cut away, except around the larva. 



Family LIMNOPHILID^ 



The larvae of members of this family are cater- 

 pillar-like, and are found in a great variety of 

 aquatic situations, but especially in ponds and slow- 

 moving streams, even in those that become dry 

 during the droughts of summer; a few, Neophylax, 

 are found in rapids. Many of the larvee that live in 

 quiet water can be kept in aquaria. 



The cases made by different members of this 

 family differ greatly in form and in the materials used 

 in their construction; in some species the case made 

 by an old larva differs greatly from that made by it 

 when young. 



In several genera of this family the larvae make 

 cylindrical cases of sticks and fragments of bark, 

 which are very irregular in form; one of these is represented by 

 Figure 700. 



To this family belong the larvae that build cases of the "log-cabin 

 type" ; these are composed of sticks or of pieces of grass placed cross- 

 wise of the case (Fig. 701). A case closely resembling this in plan but 

 differing in appearance is made of bits of moss. 



Among the larvae that change the form of their case when full- 

 grown is Limnophilus combindtus, which is described by Lloyd. Dur- 



Fig. 699.-Case of 

 Ganonema 

 amer icana. 

 (After Lloyd.) 



Fig. 700. — Case of limnophilid larva. 



Fig. 701.— Log- 

 cabin type of 

 case. 



ing early life this larva frequents the grass and sedges that fringe the 

 edges o£ streams, and makes a case of the cross-stick or log-cabin type. 

 When the time for pupation draws near, it migrates away from the 

 grassy area and makes a case differing entirely in appearance from 



