HESSIAN FLY. 
17 
May 20th; and, in the second case, on July 20th, which is the latest 
observation given of appearance from the preceding year's puparia. — Ed. 
On May 3rd Mr. Inclibald wrote :—“ I had hoped long ere this to 
have sent you types of Cecidomyia destructor ; the cases are very brown. 
I feel some moisture is essential to their development. All the Cecid 
group are lovers of moisture.” 
May 9th : “ As I told you, the pupse of C. destructor are gathering 
intensity of colour daily.” 
No further progress of alteration of appearance was mentioned 
until May 27th, when Mr. Inchbald wrote :—“ My pupa of C. destructor 
has turned very red,— glowing : its eyes are to be seen and its antennae; 
legs are all folded in their sheathing covers waiting extrusion and 
two to three days after this change the Cecids (that is, the Hessian 
Flies) began to appear out of the “flax-seeds” or puparia. 
On May 30th Mr. Inchbald wrote:—“I have reared three 
C. destructor, one male and two females. The male emerged on May 
29th, and the two females on the 30th (this morning). They begin 
their winged life very early, I expect about sunrise; at all events, the 
perfected existence is attained before six o’clock. An early riser must 
he be who intends to look on the whole transformation-scene from the 
crack first made above the thorax to the drawing out from the sheath 
of the body of the gall-gnat. I have the little silver shroud, too, in 
itself an object of beauty, protruding from the puparium.like 
molten silver, and the tracings of the little form that it has served to 
shelter so long are all there. I have examined both the male and 
female very closely ; little, if anything, can be added to your wonder¬ 
fully accurate engravings. The ovipositor is of great length, tele¬ 
scopically formed ; the colour is deepest at the abdomen, fades gradually 
away as it reaches the tip.” 
On June 1st Mr. Inchbald forwarded me a specimen of the male 
C. destructor which he had reared, in excellent condition, together with 
the pupa-case and the “ shroud ” or light film which had enveloped it 
(the imago or perfect fly) now protruding from the pupa-case, and thus 
proving the development of the Hessian Fly to take place from these 
“ flax-seeds ” or puparia, and from nothing else. 
Mr. Inchbald had now (June 1st) bred two males and two females 
from British “ flax-seeds.” By June 23rd he had reared twenty-one 
specimens (six only of them male) ; by July 1st he had reared twenty- 
five in all (seven males and eighteen females). Of these he noticed 
that they appeared early in the morning, and did not live for more 
than three or four days at the most. 
Specimens of these Hessian Flies (or, to give them the full technical 
description, specimens of the imago of the Cecidomyia destructor, Say, 
c 
