176 



HARDWICKE'S SCIENCE-GOSSIP. 



The trachea; are plainly visible, extending along the 

 back of the grub in two parallel lines, and termina- 

 ting in four spiracles of a most remarkable character, 

 two are situate posteriorly, and two on the anterior 

 part of the body. I have found them to vary slightly 

 on different individuals, in some particulars, but they 

 all bear the same general characteristic form ; they 

 are pedunculated ; those on the fore part vary very 

 considerably from those on the posterior portion, the 

 former expand into a fan-like shape, and terminate 

 with a varying number of small tubes, each of which 

 again contain two smaller tubes. I have found the 

 number of tubes to range from six to twelve on 

 different creatures, those on the posterior part of the 

 body are of lenticular form, slightly concave, and 



The grub is hatched from an egg, which in form is 

 cylindrical, very slightly curved. It measures "05 in 

 length, the surface is very elegantly marked with fine 

 reticulations, pearly white in colour, and is a very 

 pretty object under the instrument. 



The egg is deposited just under the surface of the 

 ground by the parent fly, which belongs to the order 

 Diptera, and is one of the exceedingly numerous 

 family of the Muscidae. Species ? In size it is about 

 equal to the ordinary house-fly, the males being the 

 smaller of the two ; it is of a dull greyish-green 

 colour, the upper portions of the thorax and abdomen 

 are covered with rather strong hair. In the female 

 when distended with eggs the under portion of the 

 abdomen changes slightly in colour ; under the mi- 



Fig. 104. — Grub enlarged 9 diams. 

 a, anterior spiracle ; b, posterior 

 spiracle. 



Fig. 106. — Posterior 

 spiracle. X 200 

 diams. 



jmn#. 



Fig. 107. — Anterior 

 spiracie. X 200 

 di.ims. 



Fig. 105.— Mandible, a, lower teeth in 

 position, magnified 82 diams. 



Fig. 108. — One tube, show- 

 ing position of small 

 tubules. X 680 diams. 



contain in the concavity three orifices of the ordinary 

 stigmatic form ; they are, however, much larger. I 

 should judge their capacity for admitting air would be 

 quite equal to the entire number of openings on the 

 anterior spiracles. Unlike other creatures of this 

 class I have been unable to detect any form of 

 spiracles along the sides, this clearly indicates another 

 special adaptability of means to an end, the original 

 burrow being only sufficiently large to admit the 

 grub ; air would be obtained with difficulty if the 

 ordinary arrangement were maintained, whereas, by 

 the one indicated, all difficulty in this respect is 

 obviated. 



I have taken as many as fifteen grubs from one small 

 plant ; one is the pioneer, the others follow in groups. 



croscope this change is seen to consist of alternate 

 stripes of two shades of similar colour, giving it the 

 appearance of a brownish-green ; the central portion, 

 however, is of the same nature as the upper surface, 

 and is likewise covered with stiff hairs. This forms 

 a neat pattern on each articulation, which unitedly 

 has the appearance of a fine streak. The wings are 

 strongly veined, and the lateral margin carries 

 numerous strong hairs or fine spines, which gradually 

 change into hair at the apex, and continue round 

 the opposite margin to the base. The ovipositor is 

 capable of being extended considerably, and defies 

 description by me ; the'proboscis or tongue is of the 

 usual type of this family, and the following is Mr. 

 Wood's description in his " Insects at Home." This 



