102 



PROCEEDIXGS OF THE NATIONAL MUSEUM. 



VOL. XXVIII. 



-Egg of an eriophyes 



IN GALL. 



Near the base of tlie abdomen, beneath, is the genital opening, the 

 female epigynum being quite large and prominent; the male epiandrum 

 is much smaller. At the apex of the abdomen is a truncate piece, the 

 telson, from which arise two long hairs, and sometimes other shorter 

 ones- There are also a few other hairs on the bod^'. At the tip of the 

 abdouKMi is a sucker, which can be extended or retracted at the will of 



the animal. The legs are five-jointed, short, 

 and end in a single tarsal claw, beneath which 

 is a plumose hair, known as the ''feather hair." 

 The cephalothorax often shows various lines or 

 ridges. The number of rings or annulations 

 on the abdomen varies according to the species, 

 and in some forms there are more divisions 

 al)ove than ]>elow. In size few of the Erio- 

 ph^nda; reach one-hundredth of an inch, and 

 many are not half as long. 

 The Erioph3'idte have had a checkered history. The early botanists, 

 imabk> to see the minute creatures, supposed that the galls and fuzzy 

 spots were fungi, and so described them, the genus CephaJoneon 

 being founded on distinct galls, Yolvol'tfcr on rolled edges of leaves, 

 and Er'rneuin and PJujlJerinm on the fuzzy patches. 



Duges in 1S32, who was the first to carefullv look into these galls, 

 supposed that the mites were inunature, since they had but two pairs 

 of legs. He saw the eggs, l)ut supposed 

 that the adult mite had come in the gall to 

 la}^ the eggs and then went out to deposit 

 eggs elsewhere. In 1S51 Dujardin examined 

 some galls, found the mites, and noticed 

 within some of these, objects which he 

 took to be eggs. Therefore he believed 

 these mites to ))e adults, and named them 

 Phyi()j)fiix. A few years later Scheuten 

 examined the pear-leaf l)lister, found the 

 mites, and decided that they were immature 

 forms, and that the full-grown creature was 

 an eight-legged mite that he found associ- 

 ated with them. This supposed adult lie 

 ligured and proves to be a Gamasid, which 



was doubtless feeding on the Eriophyes. Since then many observers 

 have examined these mites and confirmed Dujardin. that they are adult 

 and constitute a separate group of Acari. 



'i'hc deformations produced by mites on plants have been called 

 iiairo-eecldt'i. Nearly all such deformations are produced by members 

 of this family. The relation of th(> mite to the gall or erineum is not 

 fully known. An erineum is pi'actically a dense mass of deformed 



Fig. 19-1. — KrkiI'hves gossvpii, an- 

 terior PART OF BoOY. 



