lO THE COLORADO EXPERIMENT STATION 
MALE AND FEMALE BIRTH RECORD OF WINGED MIGRANTS 
MAIZES 
femaees 
maees 
femaees 
Louse_ 1 
4 
5 
Louse — 9 
2 
• 
4 
“ _2 
5 
5 
“ __.10 
4 
5 
“ _ 3 
3 
5 
“ ...11 
3 
6 
“ _4 
3 
5 
“ ...12 
4 
5 
“ _5 
3 
4 
“ ...13 
4 
5 
“ _6 
4 
1 
“ ...14 
3 
4 
“ _ 7 
5 
2 
“ ...15 
4 
5 
“ _8 
3 
2 
“ ...16 
4 
3 
In a state of nature these remarkable instincts and life habits 
were not developed without a very deep-seated cause. One pur¬ 
pose seems to be to enable the aphis to get away from its mortal 
foes and continue its existence. The lady beetles * and other 
predaceous enemies are likely to become so numerous late in the 
season as to exterminate the colonies of woolly aphis, but if such 
a thing should happen, the eggs deposited by the true females will 
start a number of new isolated colonies another spring away from 
the old haunts of the enemies, and in this manner greatly in¬ 
crease the probability of the continuation of the species. ProlDably 
another equally important consideration is the increase of food 
supply through the dissemination of the species. 
When cold nights come on, about as winter apples are being 
picked, many of the young lice (Fig. ii) do not locate, take on a 
dusky to dark greenish color, do not grow or secrete any cotton 
or shed their skins, and seem to be developed for the special pur¬ 
pose of withstanding the winter’s cold to start another round of 
woolly aphis life the next spring. 
If a tree top is badly infested, these specialized young will 
crawl down the trunk in countless thousands in the fall. We have 
often seen them abundant enough to very perceptibly darken the 
trunk of the tree and the earth for some inches about the crown. 
Great numbers crawl into crevices in the earth, about the crowns 
of the trees, and others get into every possible hiding place be¬ 
neath loose bark, in cavities of rotten limbs, in old scars and other 
places that will afford a little winter protection. 
Apparently, all the lice in our Colorado climate that insert 
their beaks and begin taking nourishment in the fall are killed 
when severe freezing weather comes on. By far the greater num- 
*We have found Hippodamia converg'ens to he by far the most abun¬ 
dant lady beetle attacking' this louse. Oocciiiella transversalis, C. trans- 
versoguttata, and C. moiiticola we have also found feeding upon them to 
some extent. 
