Aphids are one of the most common plant pests. By sucking on plant cells, they deprive the plant of nutrients, release harmful substances and often transfer viruses. The results are deformations (curled and crimped leaves, necroses) and discoloration of leaves and sprouts. Additionaly, aphids emit honeydew which leads to the development of sooty mold and attracts ants. In middle Europe, there are over 800 known aphid species. They may be winged (Alatae) or wingless (Apterae) and can grow up to 1-4mm. Their colours range from yellow, green and red to brown and black and depend on food and season. Aphididae have two caracteristic tubes (cornicles) at the abdomen.
The development of the pests takes about 7-14 days. They reproduce either by laying eggs (40-100 per female) or by viviparity, which accelerates the spreading. Under optimum conditions, the reproduction can literally explode (factor 12 each week).
Jung aphids go through four stages (each initiated by a mold) until maturity. The white remains of the molds (exuvia) can often be found upon and below the leaves. In heated rooms, aphids reproduce all year round.
The most common apid species are:
- The black bean aphid (Aphis fabae) has a size of 1,3-3,1 mm and a dark green to black colour. The antennas are half as long as the body.
- The cotton ahpid (Aphis gossypii) is 0,9-1,8 mm large and varies in colour from a yellowish-green to a mottled dark green. The antennas are the 0,7fold body length.
- The foxglove aphid (Aulacorthum solani) is 1,8-3 mm large and yellow to green, with dark spots at the cornicles. The lenght of the antenna is 1,5 times the body length.
- The potato aphid (Macrosiphum euphorbiae) is 1,7-3,5 mm. The colour can strongly vary from yellow and green to red and pink. The length of the antenna equals the body lenght.
- The green peach aphid (Myzus persicae) is 1,2-2,6 mm large and grey, yellow, green or red-brown. The antennas are as long as the body. The cornocles are green or dark brown and 0,6 times the body length.
- The rose aphid (Macrosiphum rosae) has a size of 1,7-3,6 mm and a green or reddish colour, with dark areas on the legs. The antennas are yellow and black.
- The oleander aphid (Aphis nerii) is 1,5-2,6 mm and yellow, with brown or black legs. The size of the antennas is 0,7times the body length.