238 Journal of Agricultural Research voi. xvi. N0.9 



When the parasite alights on the mine, the larva becomes uneasy and 

 gives several twists in an attempt to avoid the attack. Unfortunately 

 the larva is piimed between the two epidermises of the leaf and has 

 little freedom of movement. Thus, it is a simple matter for the parasite 

 to insert its ovipositor into the larva. The parasites transform within 

 the puparia and issue somewhat later than the flies themselves. 



A third parasite was reared from the eggs of P. calyptrata and deter- 

 mined by Mr. A. A. Girault as Trichogramma minutum Riley. Six para- 

 sites issued from three eggs, indicating that more than one parasite 

 develops within a single egg. 



In addition to the parasites mentioned above, a larva was attacked by 

 an adult of Nabis ferus (L.). The writer also caught a nymph of this 

 species with its beak inserted into the larva of the leaf miner, sucking 

 out the juices from its body. Nabis ferus is a predacious species and 

 has been known to attack the lar\^a of Pegomyia hyoscyami Panz., the 

 spinach leaf miner. 



DESCRIPTION OF THE STAGES OF PEGOMYIA CALYPTRATA 



Egg. — The egg (PI. 28, C) is a dirty white, glossy, elongate, and nearly 

 cylindrical in shape. It has a reticulated surface composed of polygonal 

 areas. The micropyle end is rounded or slightly flattened. The oppo- 

 site end is distinctly pointed. Length 1.18 mm. ; width 0.35 mm. 



First-stage larva. — The newly hatched lar\^a measures 1.3 mm. 

 It is creamy white in color and more or less transparent. The trachea 

 and alimentary canal are visible through the integument for the whole 

 length of the body. The first-stage larva possesses the same number of 

 segments as the mature larva, 1 2 visible segments, but the segmentation 

 is not distinct. The body is rather smooth, except for the minute fleshy 

 locomotory spines, which are located on the intersegmental areas and 

 the margins of each segment posterior to the second. These fleshy 

 spines are arranged in discontinuous thickly set rows encircling the body 

 slightly oblique to the edges of the segments. The first segment, 

 " pseudo-cephalon " (Henneguy) (PI. 30, E), bears a pair of sensory 

 papillae a short distance in front of the mouth opening. On each side of 

 the "pseudo-cephalon" there is a row of 12 to 13 minute button-like 

 areas which extend dorsally from the mouth opening. The pharyngeal 

 skeleton is slender and not as highly chitinized as in the later stages. 

 The mandibular sclerite is elongate and serrated, having about 12 sharp 

 teeth. The anterior spiracles are closed, while the posterior spiracles 

 have single breathing pores. The posterior ends of the trachea are 

 slightly chitinized and appear as two parallel chitinized bars at the poste- 

 rior end of the lar\'a and are more conspicuous than the spiracles them- 

 selves. 



