28 MASS. EXPERIMENT STATION BULLETIN 157. 



quite likely that the numbers of the insect are reduced in a measure in all 

 these ways. The fact that the insect has not been reported as an outdoor 

 pest throughout aU these years is very strong additional evidence that it 

 is only a greenhouse pest. 



LIFE HISTORY AND HABITS. 



The Adult. (Plate I., Figs. 1, 2.) 

 Description. 

 The following description, taken from Dr. Lintner's " Seventh Report on 

 the Injurious and Other Insects of the State of New York," 1891, p. 243, 

 is Kowarz's original description of the insect, made from twenty specimens 

 winch were submitted to him by Osten Sacken in 1890, and pubUshed 

 for the first time in this country in the above report : — 



Front and face yellow, occiput gray, antennae altogether black, tip of the palpi 

 generally dark, oral bristles distinct, gense narrow, hardly equal to one-third of 

 the height of the eye. Thorax and scutellum uniformly gray, sometimes the former 

 with a pale-yellow lateral stripe in front of the root of the wings; thoracic dorsum 

 usually with four pairs of dorsal macrochetse, but without the intermediate 

 acrostichal [or inner row of the dorso-central] bristles; seldom a few in the vicinity 

 of the scutellum; scutellum with four macrochetse on the edge. Wings almost 

 hyaline; veins blackish, yellowish near the root; the costal vein reaches the tip 

 of the third vein only, which tip is rather far distant from the tip of the wing; the 

 first, second, and third veins are distinct, the other longitudinal veins are thin, 

 especially the fourth, which ends in the tip of the wing; the sixth vein is incomplete; 

 the posterior cross vein is wanting; tegulae and halteres pale yellow. . Legs black 

 only the knees pale yellow; sometimes also the trochanters of the fore legs yellow. 

 Abdomen black, but little shining, the ventral sides more or less distinctly pale 

 yellow; the posterior edge of the anterior segments with an exceedingly narrow 

 pale-yellow margin; on the last segment this margin is more distinct. Genitals 

 black, those of the male of moderate size; the ovipositor of the female hardly as 

 long as the last abdominal segment. 



The following additional minor observations may be appended: eyes 

 red when insect is aUve, black when dead; wings somewhat iridescent; 

 the yellow on the ventral sides of the abdomen gradually narrowing from 

 base to apex. Whereas the abdomen in the male tapers gradually and 

 ends bluntly, that of the female ends somewhat pointedly, the last segment 

 having the shape of a truncated cone. Length of body of male 2 milli- 

 meters, female sUghtly larger; this somewhat larger size of the female is 

 especially marked during the egg-laying period. 



Accordirg to Kowarz this species bears a close resemblance to Phytomyza 

 affinis Fallen, but differs from the latter in the absence of the acrostichal 

 bristles and in the shorter ovipositor. 



Habits of the Adult. 

 In common with many other Diptera or flies, the marguerite flies lack 

 the power of strong and long-sustained flight. They crawl lazily about, 

 or make their way from leaf to leaf and from plant to plant in a skipping 



