INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



361 



Fig. 357. — Adult female of the California pear sawfly, 

 Gyriinonychus caMfornicus Marlatt, Enlarged six times. 

 (Redrawn after Marlatt) 



Control. — The application of arsenical sprays when the young begin 

 to appear is the best remedy. The second codlin-moth spraying is 

 usually sufficient to 

 control this pest also. 



PARASITIC 

 HYMENOPTERA 



Of the beneficial in- 

 sects, by far the most 

 effective are the 

 hymenopterous para- 

 sites belonging to the 

 superfamilies Iclnu u- 

 m oho idea, Cynipoi- 

 dea, Chalcidoidea and 

 Proctotrypoidea. Not 

 all of the members of 

 these superfamilies 

 are" beneficial. Some 

 like the clover seed chaleis and the wheat joint-worm are injurious 

 and many prey upon predaceous and parasitic insects. Not all the true 

 parasites belong to these four superfamilies, for, as we have seen, many 

 dipterous insects are very efficient parasites. In all the superfamilies, 

 except the Ichneumonoidea, many of which arc quite large, the mem- 

 ^^^^^ bers are usually exceedingly 



small, a hand lens or micro- 

 scope being accessary for their 

 study. 



The females usually lay 

 their eggs within, beneath or 

 attached to the outer surface 

 of the host or within the egg, 

 by means of an ovipositor spe- 

 cialized for such purposes. 

 Upon hatching, the young leg- 

 less larvae begin feeding upon 

 the body or juices of the host 

 or egg, the vital tissues of the 

 former being reserved until 

 the larvae are nearly ready to 

 pupate. 



The entire larval period is 



passed within or upon the host. 



The pupal stage may he passed 



attached or not attached to it. 



Fif 



3 ~ t "x*i AJ ,*f°' 

 358. — Various stages of the purple scale 



parasite, Aspidioti ohagus citrinus Craw. 1, e, 

 2, larva; 3, larva inside the body of the scale: 

 4, nearly mature insect. Greatly enlarged. 

 (After Quayle, Cal. Agrcl. Exp. Sta. I 



within the host 



There are great variations in the time of development, but one genera- 

 tion a year in some and many in others. The adults are usually four- 

 winged insects with quick power of flight and great activity. Many of 

 the smaller species have the ability to jump like fleas. 



The work of all true parasites is rather spasmodic because of the very 

 nature of their existence. Naturally, with the decrease in the numbers 



