16 SCALE-INSECTS 



ants, one of moderate size and the other very small, were seen at- 

 tending these scale-insects, from which they obtain a honey-like ex- 

 udation. The ants rather serve to protect the scales by warding off 

 parasites and predaceous insects. This scale-insect was noticed to 

 exude a drop of a clear honey-like fluid from the back posteriorly, 

 upon which the ants fed. 



PARASITES AND OTHER ENEMIES OF SCALE-INSECTS. 



The insect enemies of scale-insects may be divided into two cate- 

 gories : True parasites, which live internally in the host insect, and 

 predaceous insects, which attack the scales externally and devour 

 them bodily. 



The true parasites are very small members of the orders Hy- 

 menoptera and Diptera, more particularly the former in the case of 

 scale parasites. The hymenopterous parasites belong principally 

 to the families Chalcididae and Prodofrupidae, two or three spe- 

 cies of which have been more or less briefly described in the pre- 

 ceding pages. The dipterous parasites belong principally to the 

 Ochthiphilidae, a family of acalyptrate Muscidae, and perhaps to 

 some other families of the same division. These parasites deposit 

 their eggs in or upon the scale-insects, and the newly-hatched para- 

 site lives within the body of its host until full grown, when it trans- 

 forms and issues as a perfect insect. 



The chief predaceous insects, which are useful in destroying 

 scales, are the following: Coccinellidae, or lady-birds; and certain 

 predaceous lepidopterous larvae, belonging to the families Noc- 

 iuidae, Phyvitidae, Tineidae, and Pyralidac. The predaceous ene- 

 mies have proven of more value in California than the true para- 

 sites, 



Of the Coccinellidae, or lady -birds, we have here two very efficient 

 forms, which are mentioned in the preceding pages. They are 

 Coccinella oculafa, and its ashy-gray variety ( C. abdomincdis, which 

 looks like an entirely different species. The former is black with 

 a yellow spot on each wing-cover, and the head and forward margin 

 of thorax whitish. The variety is entirely creamy -jjray, with eight 



