Plant lice

“ Nicotine is the most effective chemical for killing plant-lice. Do any of the lice develop wings? If so, how many? Wings develop on some of the lice at times when a plant or crop becomes too heavily infested by them. This enables some of the lice to spread to new food plants before old plants are completely destroyed and the colony of lice starved. ”

“ A strong north west wind, at such times, is of incalculable value to the farmer. Moreover, minute flies, allied to the house fly, such as Tephritis, Oscinis, etc., now attack the young cereals, doing immense injury to grain.
Millions of Aphides, or Plant lice, now infest our shade and fruit trees, crowding every green leaf, into which they insert their tiny beaks, sucking in the sap, causing the leaves to curl up and wither. They also attack the stems and even the roots of plants, though these latter (Pemphigus, Fig. 247) differ generically from the true Plant lice. ”

“ On maturing they begin to give birth to young lice. Throughout the summer this method of reproduction continues. These summer forms are known as the stem mothers or agamic females. These are not true females for they produce living young in place of eggs and during the summer [110] no male lice are produced at all. This is nature's way of increasing the race of plant-lice rapidly. Late in the fall again a brood of true males and females is produced. During the summer the plant-lice increase more rapidly than any other type of insect.
Plant-lice vary in size, color and general appearance. ”

“ The Plant-lice or Aphides should always be collected in connection with their food-plants, and it is very essential also to collect the same species at different seasons of the year to obtain the different forms or generations, which frequently present very marked differences. It is also very necessary to secure the winged forms, which are usually produced toward autumn, and without which the species are not easily identified. The Bark lice or Scale-insects should also be collected in connection with the leaves or twigs which they infest. ”

“ Several species of the genus Aphidius of the ichneumon family, very minute parasites, destroy the lice by the thousands. Thus, plant-lice on out-door vegetation, which may threaten dire mischief early in the spring, are almost vanquished before summer comes. In some years, however, probably favored by drought, the plant-lice live out of proportion, and succeed in spite of their enemies, when they do most serious injury. They are sometimes favored, too, by misguided cultivators, who destroy their enemies, mistaking them for mischievous insects. ”

“ Ants protect plant lice of various species, which may become very injurious to many kinds of cultivated plants, inflicting serious losses for the agricultural interests; the plant lice, or aphids, secrete a sweet honey-dew juice, of which the ants are very fond ”

“ They breed rapidly and with the help of parasites and other beneficial insects usually control the plant-lice pests.
Observations and Studies
Examine about fruit trees, shade trees, truck crops and in wheat fields for the brightly marked beetles. Watch them move about the plant in search of food. Can they fly? Do you find them eating the leaves? Do you find any green lice near them? See if they feed on these lice. Examine [91] also for the soft bodied, tiger-like grubs. Do they eat the lice? Do they travel fast? Have they wings? ”

“ These beetles hide under the leaves that cluster in sheltered nooks about or between the large roots of forest trees, where they can be found on any mild winter day, and may be carried to the green-house or to the window plants that are infested with plant-lice. They will not only devour these pests, but will soon lay eggs that hatch and produce the larvæ which are so voracious as to clear the plants in a short-time. A little attention to the habits of these insects may spare us great losses from the plant-lice. ”

“ Fortunately weather conditions together with parasitic and predaceous insects hold them more or less in check. Because of the difficulty of getting at the underside of the curled leaves where these lice mostly work they are extremely hard to control. Lime and sulphur when the trees are dormant destroy as many of the eggs as it comes in contact with. A tobacco extract is quite effective as a contact spray in the growing season. The trees must be closely watched and if the lice appear in any considerable number they must be promptly attended to or serious damage is likely to result. ”

“ At this stage the outward symptoms of the disease first become manifest, in a sickly, yellowish appearance of the leaf and a reduced growth of cane. As the roots continue to decay, these symptoms become more acute, until by about the third year the vine dies. Such is the course of the malady on vines of the species vinifera when circumstances are favorable to the increase of the pest. When the vine is about dying it is generally impossible to discover the cause of the death, the lice, which had been so numerous the first and second years of invasion, having left for fresh pasturage. ”

“ Clean range, clean quarters, clean feed, and clean water are most important.
LICE AND MITES
Lice may cause high mortality among young poults, those badly infested gradually becoming weaker until they die. Head lice are the most troublesome and are found close to the skin near the top of the head, above and in front of the eyes, and under the throat. Applying an insect powder, preferably sodium fluoride, when the hen is set, is an easy method of preventing lice from getting a start among poults. ”

“ Others, not killed, are greatly impeded in their growth; the tender parts, which are attacked, become stunted and curled. The punctures of the [314] lice appear to poison some plants, producing warts or swellings, which are sometimes solid, sometimes hollow, containing within them a swarm of lice, descendants of a single individual. [28] These last are often seen upon the leaves of the Elm, and upon some Poplars, and other trees; but I have not found any upon the foliage of our cultivated fruits, unless it be those on the grape. ”

“ Persons suspected of harbouring body lice should be examined first for the actual bites of the insect on the skin. Their clothes, and especially their under-garments, should then be carefully examined, attention being more particularly directed to the seams and folds where the eggs, if present, are most likely to be found. ”

“ Then the lice, and then they die,"
is a couplet repeated in all the hop districts to-day, but the damage done by the flea is not to be compared to that caused by the next pest, the fly. The latter is one of the numerous species of aphis which begins its attack in the winged state, and after producing wingless green lice in abundance—which further increase by the process known as "gemmation"—reappears with wings in the final generation of the lice, and hibernates in readiness for its visitation in the spring next year. ”

“ But some of these diseases give great trouble to the lily grower, and often tax his patience to the utmost.
Some lilies are very prone to a form of mildew which, beginning as a minute spot of discolouration on one leaf, eventually destroys the whole of the foliage and flower-buds, and turns a beautiful, well-grown, apparently healthy lily into a brown slimy stick.
This disease usually begins to show itself about the middle of May. A small grayish transparent spot appears on one leaf, and in about a month it has spread and completely destroyed the plant. ”

“ The big gray lice will be found on a chick’s neck near the head. The remedy for this is to grease the feathers with vaseline on the head and neck. The small white lice can be controlled by dusting the chicks with insect powder and by keeping the brooder absolutely clean. A weekly coat of whitewash to which some carbolic acid has been added will keep lice in check in poultry houses and is an excellent plan. Hen-hatched chicks are usually more subject to lice than those hatched In incubators and raised in brooders, as they become infected from the mother. ”

“ Further, they often cause great cutaneous irritation and are loathsome companions. It is no easy matter to get rid of lice when infection is on a large scale, but very often this is not the case and it is possible to detect their presence only by careful examination. There is no real difference between head lice and body lice; they are simply varieties of the same insect. The presence of head lice may be recognized by the discovery of their eggs, which are known as nits and are minute, yellowish-white, goblet-shaped bodies about the size of a full-stop on this page. ”

“ Usually grass is mixed with the mud, but some swallows make their bricks without straw. A lining of fine hay and plenty of feathers from the chicken yard seem to be essential for their comfort, which is a pity, because almost always chicken feathers are infested with lice, and lice kill more young birds than we like to think about. When there is a nestful of fledglings to feed, sticky little pellets of insects, caught on the wing, are carried to them by both parents from daylight to dusk. ”

“ Lice are no doubt to be regarded as bugs, simplified in structure and lowered in animal life in accordance with their mode of living as parasites, being small, flattened, apterous, myopic, crawling and climbing, with a conical head, moulded as it were to suit the rugosities of the surface they inhabit, provided with a soft, transversely furrowed skin, probably endowed with an acute sense of feeling, which can guide them in that twilight in which their mode of life places them. ”

“ In order to combat lice properly and intelligently, it is necessary to know something about where and how they feed, live, and breed.
(a) Adult lice live on the skin and feathers of the bird and only rarely leave the pigeon. When accidentally dislodged, they crawl very short distances to other birds. Lice cannot live longer than a few days away from the birds. ”

“ This treatment will destroy both insects and eggs. After twenty-four hours the hair and scalp must be shampooed with warm water thoroughly.
CLOTHES LICE.—These insects are a trifle larger than the head lice, being one-twelfth to one- [Pg 162] eighth inch long, of a dirty, yellowish-gray color, and only infesting the most filthy people. The lice are generally only seen on the clothes, where they live, coming out on the body only to feed. ”

“ An expert eye detects the presence of the lice by the sparse and jaundiced foliage of young trees which an untrained eye would say were down with incipient yellows—indeed countless numbers of young trees have been sacrificed to the yellow's pyre when they suffered only from lice on the roots. ”

“ On the whole, however, the fungus probably gains the most, for it has been found, as we should expect, that the green cells can live and grow if separated out of the lichen, but the fungus cells die when their industrious companions are taken from them.
At any rate the partnership succeeds, as you will see if you go into the wood, or into an orchard where the apple-trees are neglected, for every inch of the branches is covered by lichens if not already taken up by mosses or toadstools.
There is hardly any part of the world except the tropics where lichens do not abound. ”

“ Female lice lay eggs (nits) along the shafts of the feathers, particularly on the primary coverts.
(d) Louse eggs hatch in 10 to 14 days.
(e) Young lice eat, molt (3 to 5 times) , and grow to maturity in about 14 days.
(3) Diagnosis. Infested pigeons are restless and constantly pick and scratch in an effort to dislodge the lice. Heavily infested birds may become weak and thin because the constant annoying movement of lice interferes with their proper relaxation and rest. Careful examination of the birds will reveal the lice. ”

“ Small flies are attracted to the spathe by the carrion-like colour and odour of the spadix, and explore the lower premises. The hairs allow easy descent, but prevent return. If the flies have already been in an Arum flower they bring with them pollen on wings and feet, and find the stigmas ripe to receive it. When these are no longer fit for fertilization the anthers open and discharge their pollen in a shower on the insects; the stigmas secrete honey as a reward to the imprisoned flies, and the upper series of hairs shrivel up and set the insects free to carry their pollen to another Arum. ”

“ The Lichens, being aerial in habit, and more insensible to changes in climate than any other plants, survive and flourish where all other vegetation would perish. The decaying parts of their bodies furnish the subsoil in which future mosses, ferns, and flowering plants can take root. Their importance, therefore, cannot be over-estimated. A Lichen (Fig. 109) is made of threads, and colorless and green spores. The threads resemble the mycelium, or threads of a Fungus; the green spores (gonidia) are like the spores of the Algae (the spores of Fungi, being colorless, resemble the other spores) . ”

“ The declining sun lighted brilliantly the eastern banks of Korus, the crimson sward, the gorgeous forest. Beneath the trees we saw feeding many herds of plant men. The adults stood aloft upon their toes and their mighty tails, their talons pruning every available leaf and twig. ”

“ So extravagant is Nature with her choicest treasures, spending plant beauty as she spends sunshine, pouring it forth into land and sea, garden and desert. And so the beauty of lilies falls on angels and men, bears and squirrels, wolves and sheep, birds and bees, but as far as I have seen, man alone, and the animals he tames, destroy these gardens. ”