TENTH EEPOKT OF THE STATE ENTOMOLOGIST 457 



they occasion on the leaves of the plants that they infest. Not all, 

 however, produce galls, some of them living within the buds and 

 arresting their development, while others occasion a singular growth of 

 curled or twisted hairs on the under side of the leaves in which they 

 live. The galls that they produce are of various forms and sizes, but 

 they frequently appear as rounded swellings or pouches on the upper 

 surface of the leaf, with a slit-like opening below, through which the 

 mites may pass in and out. They are to be found upon several of our 

 trees and shrubs and plants, as the maple, ash, the elms, oaks, linden, 

 willows, pear, grapevine, arbor vita?, verbena, etc. 



The artificers and occupants of these galls are very peculiar creatures. 

 They are exceedingly minute — most of them disclosing hardly any 

 form to the naked eye. Some of them are " so small and transparent 

 (as the Phytoptus of the ash), that it cannot be seen in the gall at all, 

 and it is only by washing out the galls and searching for them in the 

 water in which they have been washed that it can be known that there 

 have been living creatures there." Under the microscope they show 

 extraordinary structure. Mites, as a rule, possess four pairs of legs, 

 while these have but two pairs, and for this reason they were for a long 

 time regarded as the undeveloped larvoe of other species of Acarina. 

 Their legs are five-jointed, and terminate in a single curved claw and 

 an associated feathered organ. They have a tubular rostrum and a 

 pair of feeble maxillse, enabling them to feed both by biting and suc- 

 tion; their cylindrical, long, transversely multi-ringed abdomen ends in 

 a sucker capable of being extended and withdrawn. 



The Phytoptidm have recently been separated into subfamilies by 

 Dr. Alfred Nalepa, of the Royal and Imperial College, Vienna, as pub- 

 lished in the Reports of the Proceedings of the Imperial Academy of 

 Science, of Vienna. His writings have not been seen by me, but quot- 

 ing from Miss Ormerod's 17th Report, 189t, the main distinctions on 

 which divisions are based, are " on such points as the body being cylin- 

 drical, as is generally the case with the genus Phytoptus, or the abdo- 

 men being the largest immediately behind the thoracic shield, or other 

 variations of form; also on the abdomen being similarly ringed 

 throughout, or the rings broader on the back and narrower below, or 

 other variations." 



The Pear Phytoptus — P. pyri. 

 Through the kind permission of Dr. Nalepa, one of the excellent fig- 

 ures with which he has illustrated the mite and its operations, is here- 

 with reproduced. 



58 



