SYRPHIDAE OF MAINE. 237 



been found preying on the following aphids in this State: 

 Aphis pomi on apple; Pterocomma flocculosa on willow; 

 Symdobius oblongus on white birch; Aphis spiraecola on 

 spiraea ; Schizoneura lanigera on apple and Microparsus 

 variabilis and Chaitophorus viminalis. The larvae were com- 

 mon during late July and early August. Pupae were noted July 

 29 to August 2, the adults emerging ten to eleven days later. 

 The' office records show that larvae, pupae and adults occur in the 

 State almost continuously from mid-June to mid-September 

 at least. 



Egg. (Fig. 32-47, 42, 43}. Elongate-ovate in outline, sub-cylindrical, 

 narrower and truncate at micropylar end, nicely rounded off at the oppo- 

 site end, broadest in front of the middle (Fig. 32-42) ; somewhat flat- 

 tened to the surface to which it is attached, slightly humped or rounded 

 mp above (Fig. 32-41). Length about 0.9 mm,, diameter at middle 

 about 0.3 mm. Color chalk white. 



The sculpturing of the chorion consists of microscopic projections of 

 the surface arranged in lines running longitudinally-obliquely around 

 the egg. Each projection consists of a long 1 , slender, irregular body 

 (seven or eight times as long as broad) sometimes bent, with about 

 twelve to twenty slender arms reaching out in all directions from it. 

 The space between these bodies is roughly a half wider than the body 

 itself. Into these spaces the arms project, most of them meeting- 

 similar projections from the same or another body, many branching so 

 as to form a delicate network of slender white arms between the larger 

 bodies. Figure 32-43 is a fair representation of a small part of the 

 surface of the egg-shell, highly magnified. The projections are chalk 

 white, the depressions between them shaded, appearing grayish or yel- 

 lowish. The bodies are of such a size that one may count about 25 the 

 length of the egg and about 50 around it, transversely. 



Larva. (Fig 32-45, 46, 47, 48, 49, 50). Just after hatching (Fig. 32- 

 45}, length 1.2 mm., width .2 mm. to .3 mm. Shape sub-cylindrical, 

 broadest ait the posterior end, narrowing evenly to the anterior end, 

 not enlarged in the middle. Color light yellow or with a greenish 

 tinge. Body .surface wrinkled, the sides irregular. S eg mental spines 

 on the fourth to eleventh segments, inclusive, and the dorso-lateral ones 

 on the third segment, very long, slender, black; giving the young larva 

 a very hairy appearance, so far as I know characteristic of this species. 

 The posterior breathing appendages short, slightly divergent (Fig. 32- 

 45, a). No integumental vestiture. Dorsal blood-vessel faintly dis- 

 cernible in the posterior half of the body. During subsequent growth 

 these slender segmental hairs are replaced by shorter, stouter, more 

 spine-like bristles; the posterior breathing appendages are slightly ele- 

 vated becoming united on the median line ; and minute black spines 

 appear all over the dorsal surface of the body. 



