110 



CALIFORNIA STATE COMMISSION OF HORTICULTURE. 



Family Tenthredinidse (Saw-flies). In this family the females are 

 provided with a pair of saws, which are concealed in a cavity of the 

 abdomen when not in use. With these she cuts a slit in the leaves or 



stems of plants upon which she lay 

 her eggs, and it is this fact which gives 

 its common name to this family. The 



[^ \ ^^JK^x^ larvae are small, slimy-looking insects, 



somewhat resembling caterpillars, but 



\C ^ \ \ \Cv>^\ they have from twelve to sixteen pro- 



legs, while caterpillars, with one ex- 

 ception, have but ten. They are a 



7) P^ y '* I XV") serious pest upon plants infested by 



them, and examples of this family 



FIG. 105. Corn saw-fly (Cephus pygmxus). 

 a, larva ; b, larva, enlarged ; c, larva in 

 wheat stalk; d, frass; e, adult female; 

 /, its European parasite (Pachyonerus 

 calcitrator). (From "Insect Life.") 



FIG. 106. Currant- worm (Pristophora grossulairse) 



may be instanced in our common cherry-slug (Eriocampa cerasi) (which 

 also infests the pear), the rose-slug, and the currant- worm. 



Family Sirieidse (Horn-tails). This family is closely connected with 

 the foregoing family, but differs from it in the shape and uses of 

 the ovipositor. Instead of being a sawing instrument, as in the 

 former, it is a very 

 complicated and 

 effective boring 

 tool, by means of 

 which the female 

 can drill a hole in 

 the hardest wood, 

 in which she deposits her egg. The habits of the larvae are also very 

 different, those of the horn-tails being boring insects, and they some- 

 times do great damage to forest timber and shade trees. Members of 

 this family are of large size, the pigeon tremex (Tremex columba), 

 which is not uncommon in our State, being as large around as a pencil, 

 and sometimes an inch and a half in length. 



These two families are practically all of this order which are inju- 

 rious, or not beneficial to man. The gall-flies, which come next, when 

 very numerous, may do some damage to vegetation, but the extent of 

 this is trifling. 



FIG. 107. Cherry-slug (Eriocampa cerasi). a, larva on leaf and 

 larva enlarged ; b, adult saw-fly. 



