More than 2,500 species of wasps occur in 
North America. Only about 50 are troublesome 
to man. They are divided into the following 
groups: 
Hornets and yellow jackets (Vespa, Vespula). 
Polistes (no common name). 
Mud daubers (Sceliphron, Chalybion, and 
Trypoxylon) . 
These wasps build nests in or around homes— 
beneath eaves, on porches, behind blinds, in trees, 
in shrubbery, in rock fences, and in the ground. 
If someone disturbs a nest, he may get stung 
severely. 
A wasp stings by driving its needlelike ovi- 
positor into the flesh and injecting a venomous 
fluid into the wound. This causes a painful swell- 
ing that may last several days. In some cases it 
may be necessary to see a doctor. 
Most wasps kill destructive insects and are 
therefore beneficial. Polistes catch corn ear- 
worms, armyworms, and other pests, and feed 
them to their young (larvae). Hornets and yel- 
low jackets feed their young on house flies, blow 
flies, and caterpillars of a variety of moths. But 
when wasps build nests too close to the house or 
in shrubbery where children play, they should be 
destroyed. 
HOW THEY DEVELOP 
@ Hornets 
@ Yellow Jackets 
® Polistes 
Hornets, yellow jackets, and Polistes develop in 
the same way. Three adult forms exist: 
1. Fertile females (queens), which lay the eggs. 
2. Fertile males, which mate with the queens. 
3. Workers, which are females and usually 
sterile. (Workers may occasionally lay eggs 
without mating when the queen dies before the 
end of the season.) 
In the fall, queens and males leave the nest and 
mate. The males die shortly thereafter, but the 
queens hibernate in a crack in a rock, under loos- 
ened bark of a tree, in buildings, or in a hole in the 
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HORNETS AND YELLOW JACKETS are 
built more stockily than Polistes and mud 
daubers. They are black, and have yellow 
or white markings. The queens measure 
about 3% inch long; the males and workers 
are about !'/ inch long. These wasps are 
most abundant in the northern temperate 
region, but they also occur in arctic and 
tropical regions. They are feared because 
of their vicious sting. 
POLISTES are slender, elongated wasps; 
they are 3% inch to | inch long. They are 
black, brown, or red, and have a few 
yellow markings. 
MUD DAUBERS are also slender and % 
inch to | inch long. They are black and 
yellow {as in the species of Sceliphron), 
metallic blue {Chalybion), or shiny black 
({Trypoxylon). 
ground. Polistes queens also hibernate in attics 
and basements. 
The following spring the queen comes out of 
hibernation and begins flying about until she 
comes upon a suitable nest site. She then collects 
wood or vegetable fiber from nearby plants, chews 
it into a paperlike substance, constructs a comb 
consisting of a few shallow cells (later enlarged 
into a nest), and lays an egg in each cell. She 
does not lay any more eggs until her first brood 
develops. 
The eggs are long, white, and slightly curved. 
They hatch into larvae in 2 or 3 days. 
The newly hatched larvae are helpless, grayish- 
white grubs that resemble the eggs. They hang 
suspended in the cells, head downward. The 
bodies stick to the cells by means of a gluey sub- 
stance that they secrete. 
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