224 NEW YORK STATE MUSEUM 



Oligarces ulmi Felt 

 191 1 Felt, E. P. Econ. Ent. Jour., 4:477-78 



The larvae of this species were found at Nassau, N. Y., March 

 18, 191 1 in the thick, partly decaying bark of an old elm, Ulmus, 

 cut some two or three years ago. They were so inconspicuous and 

 concealed in the tissues that there was some doubt for a time as to 

 there being anything living in the bark, though one or two exuviae 

 led us to believe that larvae might be present. The infested bark 

 was brought into a warm room Alarch 20th and on the 22d a num- 

 ber of whitish transparent young appeared. By the 27th there were 

 literally thousands upon the inside of the breeding jars, crawling 

 freely upon the glass. Many perished while others doubtless re- 

 established themselves in the bark. These larvae do not appear very 

 amenable to laboratory methods, since we were unable to obtain 

 adults from a small piece of bark containing hundreds of larvae 

 clamped to a microscopic slide and kept in a small box. The few 

 placed in water under a cover-glass soon escaped. 



The first pupa was observed April 18. When discovered it was 

 standing at an oblique angle, being supported by the presumably 

 glutinous posterior extremity, since at this stage there are no clasp- 

 ing organs. The pupa soon turned and twisted, released its hold 

 and was shortly lying at a totally different angle upon the moist 

 surface of the wood. The pupal period probably extends over two 

 or three days. The pupae evidently work themselves partly out of 

 the wood before disclosing the adult. The first imagoes were found 

 April 24th, females occurring in increasing numbers until about 

 the 26th, at which time males became very numerous and continued 

 so to the 29th. The adult flies emerge almost entirely between 10 

 a. m. and noon. They display a marked preference for the light, 

 crawl freely, and when abundant run about in much the same man- 

 ner as a swarm of winged ants. They crawl easily upon the sur- 

 face of a glass cage though they frequently drop. Very little can 

 be seen of the midges except at the hours above named, even when 

 they are allowed to remain in the cage from day to day. It is prob- 

 able that the eggs are deposited shortly after the females emerge. 

 An individual may contain one to four ova, each with a length about 

 three-fourths that of the abdomen. One female dropped in alcohol 

 extruded two eggs which remained attached to the extremity of the 

 abdomen (plate 14, figure 4). 



