290 



THE WINGS OF COCCIDM 



The hind wing of Alenrodes (Fig. 296, c) has but one trachea and one 

 vein; this is doubtless the main stem of radius and tlie radial sector. 



{h) THE WINGS OF THE COCCID^ 



The tracheation of the wings of a species of Dactylopius found on cactus 

 is figured by Miss Patch (Fig. 297) ; and the definitive venation of the same 

 species is also figured (Fig. 298). The following is from her account. 



"The trachese in the wing 

 of this coccid remain distinct 

 until after the veins begin to 

 form so that the relation of the 

 two is at once discerned. One 

 vein follows the general trail of 

 the subcostal and radial tra- 

 cheae. This vein very evi- 

 dently represents the radius." 

 (In her figure it is labeled Rg. 



Fig. 297. — The tracheation of a wing of 

 Dactylopius (After Patch). 



I have taken the liberty of changing the designation to R) . 



"The second vein follows the base of the first tracheal group to about 

 the point where the medial trachea separates from the subcostal and radial. 

 The vein here takes a direct line for the middle of the caudal margin of the 

 wing. For slightly less than one-third the length of this vein it frequently 

 joins the path of the cubital trachea. This corresponds most closely with 

 media. 



"Besides these two main veins a short spur representing the subcosta 

 is present. 



"In a wing so highly special- 

 ized as the coccid wing it is not 

 improbable that the trachea- 

 tion has lost its value as a basis 

 for the venation. Certainly 

 in the species studied there 

 seems no necessary connection 

 between the tracheas and the 

 veins which are found later." 



The fact that the medial trachea is a member of the costo-radial group 

 of trachese suggests, in the light of the condition found by Funkhouser in 

 the Membracidae, that perhaps in the Coccidce a transverse basal trachea 

 has not been developed. 



Fig. 298. — The venation of a wing of 

 Dactylopius (After Patch). 



