February, '13] QUAYLE: red spider enemies 85 



Afternoon session, Thursday, January 2, 1.30 p. m. 



President W. D. Hunter: The first paper on the program will 

 be presented by Mr. H. J. Quayle on, "Some Natural Enemies of 

 Red Spiders." 



SOME NATURAL ENEMIES OF SPIDERS AND MITES 



By H. J. Quayle 



Red spiders and mites, exposed as they usually are throughout their 

 lives on the surface of the leaves or fruit, and not being very active, 

 are subject to the attacks of a considerable number of enemies. Those 

 that I will consider in this paper were observed to feed upon the 

 spiders and mites of citrus trees in the citrus belt of southern Cali- 

 fornia. The thing that seemed most striking in making these observa- 

 tions was the unusual variety of enemies, insects belonging to groups 

 that we know best as not being predaceous. Thrips are certainly 

 better known as plant enemies rather than as predaceous insects. 

 Likewise members of the family Itonididse (Cecidomyidse) are better 

 known on account of their gall-making habits and attacks on living 

 plants, rather than as parasites. Staphylinid beetles are most familiar 

 as feeders on decaying vegetable and animal matter, while a much 

 smaller number are known to be predaceous. All members of the 

 family Coniopterygidse are predatory, but their habits are so little 

 known that they are no less interesting than the others. In addition 

 to these there are the usual Coccinelids, Hemerobiids, Chrysopids, a 

 predaceous bug (Thriphleps insidiosus), mites and also a secondary 

 Hymenopterous parasite, a chalcid. 



The enemies of spiders as thus far investigated in a little corner of 

 the extreme southwestern part of the United States, and only a begin- 

 ning has been made, include, aside from several species of Acarina, 

 representatives of six insect orders, the Neuroptera, Thysanoptera, 

 Hemiptera, Coleoptera, Diptera and Hymenoptera. I will consider a 

 few of these that are least known. 



Conventzia hageni Bks. This Coniopterygid is one of the common- 

 est enemies of spiders in the southern California citrus section. It 

 feeds on the spiders both in the larval and adult stages. 



The eggs are of a pinkish yellow color, oval in shape and are de- 

 posited singly on the under surface of the leaves. From six to eight 

 days are required for them to hatch. The larva completes its develop- 

 ment in from 18 to 22 days during which time, according to our 

 observations, it molts three times. All stages of the spider are attacked, 

 including eggs, young and adult. In attacking the eggs the mandibles. 



