MITES WHICH DESTJv'OY .SCAEK-INSECTS. 81 



ridge like the jieak of a rool". The ;uiteiii);e are bhick, i)aler outwards. 

 Head porcehihi-wliite ; tlie eiihirged lirst Joint of the aiitemue, and also 

 a triangular spot on the head at the base of each antenna ])ur])le red; a 

 band of the same color on each side of the thorax. 



UfHls. — The eggs are laid upon various parts of the tree, often near a 

 colony of Plaut lice, in groups of five to fifteen, each supported on the 

 end of au erect, bristle like stalk, about 0.4 inch in length. The object 

 of this device is said to be the i)reservation of the egg from the young 

 of its own kind, for such is the rajiacity of the larva that those first 

 hatched would immediately devour the remaining eggs if they were de- 

 posited within reach upon the surface of the plant. 



Lifehis-tory. — The developnu^it of Chrysopa is quite rapid in hot 

 weather, and is greatly retaided by cold. There are apparently but 

 two broods each year, in spring and fall. Eggs are seen as late as the 

 middle of July, but the larva' oidy are abundant in midsummer. In 

 winter both larva^ and eggs are found, but the perfect insect is not 

 common except in early summer and late in the fall. There are said to 

 be several species of Chrysopa frequenting the Orange, which, howevei', 

 are with ditiiculty distinguished from each other, and have identical 

 habits. One of these has been described as new by Ashmead under 

 the name Chrysopa citri. 



r((rasite.s {PeriUtti.s sp.).'' — A Ibur-winged paiasite destroys the Chry- 

 sopa, and issues from its cocoon. It is of slender form, with the abdo- 

 men stalked ; color beneath light yellow, above black, with yellow mark- 

 ings; the legs yellov., the antennae dark, the face yellow; eyes, ver- 

 tex, and back of the head black; the rings of the hind-body are alter- 

 nately black and yellow. Length, 3""" (^\fy inch). 



Hemerobius. — Several species of this genus, which is closely allied 

 to Chrysopa, exist upon orange trees and feed ujion the young of Bark- 

 lice, and to a still greater extent upon Plant-lice (/ijj/»'.s'). They have 

 nearly the same habits as Chrysopa, but the larvie do not i)rotect them- 

 selves with a covering of fragments. The larva* are mottled with gray, 

 brown, and (bill r(>d. and are more slender than those of the ])reccdiiig 

 species. 



The pupa is formed in a globular cocoon of white parchment, not 

 covered with fragments. 



The perfect insect is much smaller than Chrysopa; the wings are less 

 trans}>arent, and are covered with do\yn of light-brown color. 



MITIi:S—ACAniN.I. 



Next to their internal ])arasites. Mites constitute the most impoitant 

 enemies of Scale-insects, and exert a constant and very i)owerful influ 

 ence in checking their increase. They are at all times present wherever 

 Scale-insects exist, and in numbeis limited only by the food supply. 

 They (;annot i)enetrate the harden(*d shells of mature Scale-insects, but 

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