FLIGHTS AND FRIVOLS OF THE APHIDS 



EDITH M. PATCH 



Entomologist, Maine Agricultural Experiment Station 



The Seasonal Migrations of Hosts of " Green Fly" Bothers the Gardener Who 

 Wonders "Where They Come From." Strange Stories of Alternating Habitations 



* E ARE all familiar with at least the main facts concern- 

 ing the seasonal travels of certain animals. The purple 

 martin, rejoicing in his return to the north with a 

 yr^j triumphant, " I'm here ! I'm here !", and that annual 

 first Penobscot River salmon, caught in the pool below the falls 

 and sent as a gift to the President of the United States, are as 

 surely obvious hints that the movements of animal life are 

 calendared as the coral tassels of the Maple, or — in those few 

 haunts where ruthless depredators have not yet completed its 

 destined extermination! — springtime's sweetest token, the fra- 

 grance of Arbutus. 



That insects have a share in the itinerary of the seasons is not 

 so generally known, though now and then a northern country- 

 man stops in late summer to admire a gathering of Monarch 

 Butterflies flocking bird-like about some low tree and taking 

 brief hovering flights while biding the long flutter to the south- 

 land. It is not, however, journeys from cold climate to warm 

 with which the seasonal flight of the aphid has concern; but 

 round trips of a mile more or less, from one sort of food plant 

 to another with stop-over privilege. For the migratory aphid 

 requires a change of conditions entailing a new diet in the spring 

 or early summer, and again in the fall in order properly to com- 

 plete the life cycle of the species. 



Little as is generally known about the habits of these mar- 

 velous insects, the aphids themselves are recognized by every- 

 one who has much acquaintance with plants; for they are nu- 

 merous in species and abundant in individuals, and common 

 enough to attract attention even while the secrets of their lives 

 are hidden from all except the detective who has patience enough 

 to follow the clue. 



Familiar to all observers of the American Elm are terminal 

 clusters of leaves bunched into rosettes at the tip of the branch 

 (see illustration). Such a deformation constitutes a shelter 

 for a family of aphids during 

 their spring residence there. 

 The mother of the colony is a 

 plump insect of dark com- 

 plexion, though by virtue of a 

 coat of powder she appears 

 much paler. She passed the 

 winter in the egg stage hidden 

 in the crevices of the Elm 

 bark. In the spring, hatching 

 from the egg just as the leaves 

 are unfolding, she sought a 

 suitable tip, punctured it with 

 her beak and by simply re- 

 maining and feeding caused it 

 to form the protective habi- 

 tation for herself and her 

 young. These, unlike their 

 mother, are born alive instead 

 of being hatched from an egg. 



HER progeny are all fe- 

 males. Upon attaining 

 their growth these give birth 

 in turn to living young, also 

 all females. All the descend- 

 ants of the original aphid or 



SUMMER AND WINTER 



RESIDENCES OF SOME OF OUR BEST KNOWN AND 



MOST UNPOPULAR PLANT LICE 



PRIMARY HOST PLANT 



SECONDARY HOST PLANT 



NAME OF APHID 



Elm (Ulmus americana) 



Apple, Hawthorn, . Mountain 



Ash 

 Juneberry (Amelanchier) 



Schizoneura lanigera 



Elm (LUmus americana) 



Schizoneura americana 



Elm (Ulmus campestris) 



Currant, Gooseberry (Ribes) 



Schizoneura ulmi 



Elm (Ulmus americana) 



Grass (Aira and Agrostis) 



Tetraneura graminis 



Elm (Ulmus montana) 



Grass (Echinochloa) 



Tetraneura ulmi 



Maple (Acer saccharum) 



Alder (Alnus incana) 



Prociphilus tessellata 



Ash (Fraxinus pennsvlvani- 







ca) 



Fir (Abies balsamea) 



Prociphilus venafuscus 



Cottonwood (Populus sp.) 



Beets (Beta vulgaris) 



Pemphigus betae 



Poplar (Populus deltoides) 



Lettuce (Lactuca) 



Pemphigus bursarius 



Poplar (Populus occidenta- 







lis) 



Buttercup (Ranunculus) 



Thecabius populicondup- 

 lifolius 



Skunk-bush (Rhus triloba- 



ta) 

 Currant (Ribes aureum) 



Wheat, Oats, Barley, etc. 



Rhopalosiphum rhois 



Lettuce, Sow Thistle (Sonchus) 



Rhopalosiphum lactucae 



Russian Olive (Elaeagnus) 



Persicaria 



Rhopalosiphum hippophae 



Plum (Prunus) 



Arrow-head (Sagittaria) 



Rhopalosiphum nymphaeae 



Russian Olive (E'.aeagnus) 



Canada Thistle (Cirsium ar- 







vense) 



Myzus braggii 



Peach, Plum, Cherry 



Potato, Cabbage, and others 



Myzus persicae 



Willow (Salix) 



Parsnip 



Aphis saliceti 



Apple (Pyrus) 



Rib Grass (Plantago) 



Aphis mahfoliae 



Apple (Pyrus) 



Oats, Wheat, etc. 



Aphis avenae 



Choke Cherry (Prunus) 



Oats, Barley, etc. 



Aphis pseudoavenae 



Apple (Pyrus) 



Clover (Trifolium) 



Aphis bakeri 



Hawthorn (Crataegus) 



Clover (Trifolium) 



Aphis crataegifoliae 



Plum (Prunus) 



Grass (Panicum, Setaria) 



Aphis setariae 



Plum (Prunus) 



Thistle (Cirsium lanceolatum) 



Aphis cardui 



Spindle Tree (Evonymus) 



Bean, other plants 



Aphis rumicis 



Plum (Prunus) 



Hop (Humulus) 



Phorodon humuli 



Plum (Prunus) 



Grass 



Hyalopterus arundinis 



Rose (Rosa) 



Potato and others. 



Macrosiphum solanifolii 



Rose (Rosa) 



Oats, Wheat 



Macrosiphum granaria 



Rose (Rosa) 



Grain 



Macrosiphum dirhodum 



Black Haw (Viburnum) 



Grape (Vitis) 



Macrosiphum illinoiensis 



Currant (Ribes) 



Lettuce, Endive, etc. 



Macrosiphum lactucae 



"stem-mother" as she is called, ordinarily remain in the same 

 cluster of leaves, which become much distorted in consequence 

 and crowded with the numerous family. As each individual 

 casts its skin several times in the process of its growth, and as the 

 discharge of honeydew is abundant, the rosette after a time con- 

 tains considerable waste matter which causes it to look untidy 

 within. Conditions are kept remarkably sanitary, however, by 

 the aid of the waxy secretions of the aphids, particles of which 

 cover the honeydew so that the liquid rolls about in white coated 

 pellets without drenching the insect. A further protection is 

 afforded also by the waxy powder which remains upon their 

 bodies rendering them impervious to moisture. 



The earlier members of the family, including the stem-mother, 

 are all wingless. In June, however, comes a generation that 

 with maturity develops wings! These late individuals, or 

 "spring migrants" as they are called, resemble the apterous 

 generations previously mentioned in being all females, but they 

 are smaller bodied and differ in various structures as well as in 

 having wings. And instead of remaining in the leaf cluster with 

 their relatives, they take flight, seeking fresh vegetation for the 

 establishment of the summer colonies. They are strong on the 

 wing and probably fly to distances of at least a mile if they do 

 not find a suitable location nearer at hand. And when they 

 desert the Elm leaf which has furnished sap for their develop- 

 ment, they are "instinctively" led to an entirely different habi- 

 tat, namely the Apple tree, the Hawthorn, or the Mountain 

 Ash (all Pyrus species). 



Finding one of these trees, the migrant alights on a leaf, 

 crawls to the underside and remains there quietly while giving 

 birth to young which seek some tender place on the branch or, 

 by preference, a "water sprout" before settling to feed. And 

 these summer colonies of our aphid of Elm and Apple, like their 

 spring antecedents, are composed only of females; and the im- 

 mediate progeny of the mi- 

 grants are wingless and have 

 their bodies whitened by the 

 secretions of the wax glands. 

 These fine waxy filaments 

 now fluff out in a white mass 

 about the insects, however, 

 whence they are commonly 

 known at this period as the 

 "woolly aphids of the apple," 

 — in many parts of the world 

 the worst pest with which the 

 orchardist has to contend. It 

 is not, however, the economic 

 significance of this insect with 

 which the present discussion 

 is concerned, but its life his- 

 tory with reference to the 

 remarkable migration from 

 Elm to Apple and return. 

 For late in the season a 

 generation of winged females 

 is developed on the Apple. 

 These are the "fall mi- 

 grants," in appearance very 

 much like the spring mi- 

 grants; and they in turn 



IOO 



