REPORT OF THE STATE EiNTOMOLOGIST I9O9 87 



There are a number of tiny, 4-winged, parasitic wasps which 

 subsist entirely on plant lice. These beneficial insects deposit 

 their eg'gs in their victims, one in each, and the maggots de- 

 velop rapidly at the expense of the host. The infested aphids 

 are easily recognized by the greatly swollen, frequently glob- 

 ular and usually brown abdomen. Occasionally a very large 

 proportion of the many plant lice on individual branches, or 

 even entire shrubs or trees, are affected in this manner. Each 

 plant louse perishes, while the maggot within, before com- 

 pleting its transformations, faste'ns the body of its host to the 

 plant. The parasite itself, as it escapes, cuts a characteristic, 

 circular orifice, leaving the central portion or lid attached by a 

 narrow hinge. It is therefore very easy to estimate the pro- 

 portion of plant lice destroyed by these parasites. 



In addition to the above, the voracious larvae of the extremely 

 delicate, lace-winged flies, destroy hosts of aphids. The golden 

 eyed parent insects are usually light green and easily distin- 

 guished by the large wings adorned with numerous minutely 

 spined veins. They deposit their oval, whitish eggs in pic- 

 turesque gTOups on leaves or twigs, each egg supported by a 

 slender, threadlike stemi nearly an inch long. The larvae are 

 rather flattened, 6-legged creatures, usually variably marked 

 with brown and yellow, and remarkable because of the greatly 

 produced jaws. Plant lice and other small insects are seized 

 in these enormous jaws and quickly perish as the body juices 

 are drawn through the hollow cavities of the mandibles. 



Remedial measures 



The experience of the last few years has demonstrated the 

 futility of depending upon the ordinary winter or early spring 

 applications of lime-sulfur washes for the destruction of aphid eggs 

 upon our fruit trees. There may be some reduction but the 

 percentage killed in this manner is so small as to be practically 

 negligible. 



Most fruit growers are thoroughly familiar with the curling 

 leaves quickly following plant lice outbreaks, and appreciate 

 the difficulty of destroying the insects after the attack has 

 progressed thus far, owing to the impossibility of hitting the 

 plant lice with any contact insecticide. Experience has demon- 

 strated time and again, the practicability of destroying these 

 minute enemies of our plants, by thorough applications of con- 



