52 MISC. PUBLICATION 336, U. S. DEPT. OF AGRICULTURE 



roots of aquatic plants, through which they obtain air. The pupae 

 also have breathing tubes specially modified for penetrating the soft 

 tissues of the plant, to which they remain attached until ready to 

 transform to the adult stage, when they rise to the surface. 



Because of their habits, which are unique among mosquitoes, the 

 larvae cannot be reached by ordinary surface larvicides such as oil. 

 In experiments carried out by the writers in Florida, partial control 

 has been obtained with common salt and with soap emulsions of 

 pyrethrum extract in oil, but the results have been variable and the 

 methods were not sufficiently economical to be feasible. In limited 

 areas practical control can be obtained by destroying the host plants 

 or by draining the ponds for a short period during the winter or early 

 in the spring before the adults emerge. 



As Mansonia larvae are often difficult to locate, the following notes 

 are given on the methods found by the writers to be successful in 

 collecting them (98). Since the larvae of M. perturbans have the 

 habit of detaching themselves when their host plants are disturbed, 

 they are likely to be missed if only the roots of such plants are 

 examined. It is therefore necessary to search for the larvae in the 

 bottom muck and trash of a pond area from which the host plants 

 have been uprooted. This material may be scooped up with a large 

 strainer and then examined in small quantities in shallow pans of 

 clear water. As the larvae usually stay on the bottom of the pans, a 

 careful search must be made. The white color of the larvae and their 

 continuous movements aid in locating them among the trash. The 

 collection of the larvae of M. titillans, which attach themselves to the 

 roots of a floating plant (waterlettuce), is much simpler. These are 

 readily taken by lifting the host plants quickly into a pan of water 

 for examination, or the plants may be lifted from the water by bring- 

 ing the dish up under them. Some larvae usually remain attached 

 to the roots, while others are found moving about in the dish. Speci- 

 mens of M. perturbans are also found at times on the same plant. 



Mansonia adults have very broad wing scales, mixed brown and 

 white, and the proboscis and tarsi^ are banded. The abdomen is blunt 

 at the tip and lacks the longitudinal stripe of white scales found in 

 Aedes soWcitans. The two species found in this region are placed 

 in separate subgenera, titillans in subgenus Mansonia and perturbans 

 in Coquillettidia. 



MANSONIA PERTURBANS (Walk.) 



This speckled brown and white mosquito is widely distributed in 

 the Eastern and Southern States. The adults are strong fliers and 

 severe biters, and in many localities become a serious pest. The eggs 

 are laid on the surface of the water in rafts similar to those of Gulex. 

 Breeding takes place in marshes and lakes having a thick growth of 

 aquatic vegetation, to the roots of which the larvae and pupae at- 

 tach themselves. Larval development is extremely slow, and the 

 winter is spent in this stage. The pupal period is also long for 

 mosquitoes, lasting 5 or 6 days. 



Throughout most of its range this species is believed to have only 

 a single generation each year, a large proportion of the adults emerg- 

 ing over a comparatively short period late in the spring or early in 

 the summer. In the vicinity of Lake Apopka in central Florida, 

 adults are present from March to December, a peak of abundance oc- 



