The male anopheline.—While certain characteristics of the male are used to separate the Aedinae from other subfamilies, yet it is only with the female that we concern ourselves in differentiating the Culicinae from the Anophelinae. Therefore, it is first necessary to distinguish the male from the female. If the antennae have not been torn off, this can be decided by the highly adorned plumose antennae of the male, those of the female being sparsely decorated with short hairs. The palpi of the male Anopheles tend to be clubbed, while those of the Culex are straight. If the antennae have been broken off, look for the claspers at the end of the abdomen.
Male mosquitoes do not feed on blood but on fruits and flowers instead. The puncturing parts of the male are not sufficiently resistant to penetrate the skin.
The female anopheline.—Having determined that the insect is a female, we then proceed to place it either in the subfamily Culicinae or Anophelinae by a study of the relative length of the palpi to the proboscis. If the palpi are much shorter than the proboscis, it belongs to the Culicinae; if about as long or longer, to the Anophelinae. The palpi of the female Megarhininae are also long, but the proboscis is curved.
Having settled on the subfamily, we separate the genera by considering such points as character and distribution of scales on back of head, wings, thorax, and abdomen; banding of proboscis, legs, abdomen, and thorax, shape of scales on wings, and location of cross veins.
Fig. 11.—Resting posture of mosquitoes; 1 and 2, Anopheles; 3, Culex pipienes. (After Sambon.) From P. H. Reports.
Anophelinae show abundant upright forked scales on occiput. The mesothorax shows sparse hairs or scales with a smooth scutellum. As a rule, the wings are spotted (dappled) and the location of these spots gives the best clue to the different species of the genera. With the exception of Bironella the first submarginal cell is large. This cell is longer than the second posterior one.
In the resting position Culex allows the abdomen to droop, so that it is parallel to the wall. The angle formed by the abdomen with head and proboscis gives a hunchback appearance.
Anopheles when resting on a wall goes out in a straight line at an angle of about 45°. It resembles a bradawl.
The scutellum of Anopheles is simple, that of Culex trilobed. Anopheles has but one spermatheca; Culex has three.