262 STATE BOARD OF AGRICULTURE. 



MOSQUITOES AND OTHER INSECTS OF THE YEAR 1902. 



BY R. H. PETTIT, B. S., ENTOMOLOGIST. 



Special Bulletin No. 17. 



It would be diflScult indeed to look back to the time when mosquitoes 

 have not been a nuisance; when they have not rendered life miserable 

 to man and beast; when they have not been a menace to health and 

 even to life itself; and yet during all these generations their torments 

 have been endured and manj' of our ancestors have died from diseases 

 spread by these pests. 



It is only in very recent years that attention has been directed 

 toward experiments relative to their destruction and toward inves- 

 tigations as to their ability to carry disease from one individual to 

 another. We are indebted to Dr. L. O, Howard for starting and main- 

 taining the experiments in relation to killing the pests. 



The life-history of the mosquito is well known in a general way. The 

 eggs of the common Culex or non-malarial mosquito are laid in raft-like 

 masses on the surface of still water, being stuck together side by side 

 in large numbers, sometimes more than three hundred in a mass. The 

 eggs of the malarial mosquito. Anopheles, are said to be laid separately 

 on the water without being joined into a raft-like body. These eggs 

 hatch usually in one or two days, by openings or lids on the under side, 

 giving forth small wigglers. The wigglers are so common and so 

 well known that a description seems superfluous, slender little crea- 

 tures, each with a swollen thorax and a head at the lower end, and 

 with a slender breathing tube at the upper end, which tube is thrust 

 up through the surface of the water to obtain air. Usually the larva 

 rests at the surface of the water, its breathing-tube projecting above 

 the surface film, leaving the head free- to feed on microscopic plants 

 and animals. After a time, varying from a week to several months, 

 the larva changes to a pupa. The skin of the larva splits and the 

 robust, swollen pupa emerges. In this condition the insect breathes 

 by means of two trumpet-shaped tubes which project from the shoul- 

 ders. After about two days more the pupal skin splits down the back, 

 and spreading open, allows the adult winged mosquito to emerge, using 

 the old pupal skin as a support on which to stand while drying her legs 

 and wings. After this is accomplished, the adult Hies away to mate, 

 lay the eggs for a future brood, and if she is fortunate enough, to taste 

 human blood. 



As has been hinted, we have here in Michigan a number of different 

 kinds of mosquitoes. The commoner sorts belong to the two genera, 

 Culex and Anopheles, the former are by far the more numerous in 

 summer time and are the ones usually seen in the open and during the 

 day time. They are not known to carry the germs of disease but are 

 classed simply as nuisances. Anopheles, on the other hand, seems to 

 prefer such localities as are sheltered by trees, houses, etc., and while 

 it will bite during the day time, it is more apt to choose the night 

 for its excursions. The two genera can easily be distinguished by an 

 examination of the mouth-parts. In Anopheles the palpi are nearly as 



