IOWA ACADEMY OF SCIENCES. 225 



COGGING. 



In this sub-family the adults are usually active and remain 

 distinctly segmented through life, but in Kermes they become 

 fixed. The body terminates in a pair of lobes, bearing bristles, 

 and there are no anal plates. 



In Orthezia the body is covered with calcareous plates of very 

 regular pattern, while in Dactylopius there is a waxy secretion 

 of a mealy appearance, easily detached, but usually forming 

 quite definite marginal appendages on each segment. 



Kermes differs from both these in losing the segmentation 

 of the body in the adult females, the body becoming globular, 

 gall like, and attached by a narrow ventral line. 



Orthezia amerlcana Walk. 



The insect referred to this species has been noted at Ames 

 in considerable numbers on one or two occasions, but it must be 

 generally scarce. The genus to which it belongs is peculiar 

 in that the secretion from the body wall forms long parallel 

 filaments or lobes, completely hiding the insect, and is calcare- 

 ous in composition. 



Dactylopius longispinous Targ. 



The common mealy bug of greenhouses, while not indige- 

 nous, is so fully established everywhere that it must be recog- 

 nized as belonging to our fauna. It is about five mm. long, 

 oval in form and covered with a white mealy powder. The 

 long thread-like appendages extending backward separate it 

 from the following species. 



Dactylopius citri Rossi. 



This species is found occurring in the greenhouse at Ames, 

 on Dieffenbachia and foliage plants. It is easily separated from 

 the preceding by the short marginal appendages. 



Dactylopius trifolii Forbes. 



A species found here on clover some years ago, but of which 

 no perfect specimens for determination were available, may 

 quite certainly be referred to the form described from the same 

 plant by Professor Forbes. It has never been observed in 

 great abundance and probably does not rank as a very destruc- 

 tive species. 



