250 ECONOMIC ENTOMOLOGY 



Eggs. — Minute, cylindrical, pale red; laid singly or in clusters in 

 crevices of wheat heads in June and hatch in about a week. 



Larva. — A short oval orange-yellow maggot, ^{2 inch long; as a 

 rule it leaves the head after feeding for 3 or 4 weeks and goes into the 

 ground where it remains in a mustard-seed-like cocoon. 



Pupa. — Pupa case small, about the size of a mustard seed, in the 

 ground; formed in June shortly before the emergence of the adult. 



Broods. — At the end of June the adult flies lay their eggs in the 

 crevices of the wheat head; the eggs hatch in about a week, and the 

 larvae feed on the milky juices of the developing kernels for about 3 

 or 4 weeks; some descend to the ground where they form minute 

 puparia which remam until the following June; others remam and are 

 carried out in the screenings at threshing time. Only one brood a 

 year. 



Control. — Burn or feed screenings; plow stubble deeply after harvest; 

 rotation of crops; sow wheat early. Dry weather unfavorable and 

 moist weather favorable for the development of the insect. 



SYRPHID^ (SYRPHIDS OR FLOWER FLIES) 



The Syrphids or Flower Flies are most valuable enemies of many 

 injurious forms of insects. They are usually bright colored and they 

 feed upon the pollen and nectar of flowers. Their maggots are often 

 found in colonies of plant-lice, upon which they feed. Some syrphid 

 larvae live in filth and are known as "rat-tailed maggots." 



C. L. Metcalf ("Syrphidae of Maine," Bull. 253) notes five types of 

 Syrphid larvae: 



1. The Aphidophagous type with body narrowed anteriorly, sub- 

 cylindrical and flattened ventrally {Allograpta and Syrphus); 



2. The boring type, with body nearly cylindrical (Merodon). 



3. The short-tailed filth-inhabiting type {Syritta). 



4. The rat-tailed filth-inhabiting type {Eristalis). 



5. The Microdon type, with body hemispherical in form. 

 Aphid-feeding species are Syrphus americanus, Allograpta obliqua, 



SphcBropnoria cylittdrica, Didea fasciata, S. stanthostomus (Fig. 150). 



The following genera live, in larval condition, in decaying vegetable 

 or animal matter: Eristalis, Platychirius, Orthoneura, Criorhina, 

 Syritta. (Consult "Syrphidai of Ohio" and "Syrphidae of Maine" by 

 Metcalf.) 



