Carpenter et al.: Mosquitoes of Southern U. S. 



17 



hand, place it on the partially separated tip of the abdomen, and by gentle, 

 intermittent traction, draw out the alimentary canal with attached Malpighian 

 tubules and ovaries into the droplet of saline. Set aside the remainder of the 

 specimen in physiological saline for salivary gland dissection. 



Pv 



D-D 



Fig. 5. Internal anatomy of a female mosquito (adapted from Marshall. 1938). 

 Ac-G, accessory gland; D-D, dorsal diverticula; H-G, hmd-gut; M-G, mid-gut; 

 M-T, malpighian tubules; Oe, oesophagus; Ov, ovary; Ov-D, oviduct; Ph, pharynx; 

 Ph-P, pharyngeal pump; Pv, proventriculus ; S-D, salivary duct; S-G, salivary glands; 

 Sp, spermatheca; V-D, ventral diverticulum. 



Prepare the mid-gut for examination for oocysts as follows: Carefully sever 

 the digestive tract at the point of origin of the Malpighian tubules and transfer 

 the mid-gut to a fresh drop of saline, discarding the Malipghian tubules, 

 hind-gut, ovaries and other debris; apply cover slip; remove excess saline 

 with filter paper. Transfer the slide to a compound microscope and carefully 

 examine the stomach wall for the presence of oocysts. The younger forms of 

 oocysts are clear, oval or round bodies and contain distinct pigment granules; 

 larger forms are similarly shaped but have distinct cyst walls and contain 

 pigment clumps. The mature oocysts have lost their pigment and are filled 

 with hundreds of slightly curved sporozoites. Before calling a slide negative, 

 the mid-gut should be rolled over by sliding the cover slip so that all surfaces 

 may be observed in profile. 



Salivary glands. — Place the remainder of the specimen in a drop of physio- 

 logical saline tinted with methylene blue and orient it so that the head will 

 point away from the observer. With a needle held in the left hand, press 

 down on the thorax across the region of the mid-coxae, causing the neck to 

 bulge slightly; at the same time, with a needle in the right hand, transfix 

 the head capsule, and with gentle traction, pull the head away from the 

 thorax. As the head tears away, a small tag of tissue will be seen attach-'d 

 to the head. This tag should contain the glistening, blue-stained salivary glands. 

 If the glands do not come out with the head, they may be recovered by 

 carefully tearing away tissues in the prothoracic region. Transfer the glands 

 to a fresh drop of physiological saline, apply cover slip and remove excess 

 saline with filter paper. 



Examine the salivary glands as follows: Using the dissecting microscope, 

 center the glands in a low-power field and crush them by pressing on the 



