December, '16] hungerford: sciara maggots injurious 543 



color, but turns to pearly white in the course of a couple of days. 

 About this time the head of the future maggot shows up as a shadowy 

 patch that grows darker until by the end of the fifth day it is black and 

 shiny and the embryo is active within this chorion. The eggs hatch 

 in six days. In Plate 41, figure 4, is shown some egg clusters as they 

 were laid in a small crevice of a potato; and Plate 41, figure 2, shows 

 a female in act of laying — about two times natural size. 



Larva 



The larva when first hatched measures .65 mm, in length and is 

 transparent. As soon as it begins to feed, the digestive tract shows as 

 a dark line through the body. As it grows the body begins to take on 

 a white color which is due to the large fat bodies within. Sciara 

 maggots are characterized by their white bodies and black shiny heads. 

 When grown the maggots measure about six or seven mm. in length 

 and have the appearance shown in Plate 41, figure 5.. About the elev- 

 enth or twelfth day, they begin to spin their cocoons which consist of 

 a few threads of silk binding together loose bits of earth, fibre and the 

 like. Larvae of all stages have the power to spin out sheets and 

 fibres of silk and sometimes use this power to form a cover to a tunnel 

 in which they work. The larva preparing for pupation spends twelve 

 hours or more making a very flimsy cell which is only a little more than 

 two-thirds its length. 



Pupa 



Before pupating, the larva contracts to about 4 mm. and after 

 a quiet period of some hours, changes to a naked pupa which is milky 

 white in color. This gradually changes until just before emergence of 

 the adult, the thoracic part is black and the abdomen shows the pattern 

 of the adult. The pupal stage lasts from five to six days. Pupation 

 usually takes place near the surface of the soil, though pupae are not 

 uncommonly found deep down in the earth — indeed, adult flies are 

 sometimes found imprisoned in deep spaces. The pupse usually work 

 their way to an open space before coming forth as adults. For this 

 reason the surface of infested soils are often strewn with empty pupa 

 cases. 



Adults 



The adult male and female of Sciara coprophila are shown in 

 Plate 41, figures 1 and 3. These photos show their relative size and 

 characteristics. 



The female of this species measures about 3 mm. and the male 

 measures 2.5 mm. Both are very active and are rapid runners though 

 weak flyers. They are prone to hide under bits of earth or leaves on 



