Frequency

We know from the letters sent to the Danish National Pest Infestation Laboratory, at what time of the year each animal is causing problems. Fig. l shows that many of the pests are mainly linked to the warm season but also that some animals (dogs fur mites, itch mites and head lice) is apparently most frequent during the winter.

This can also vary from year to year. For mosquitoes, this variation is primarily caused by difference in the amount of water in the puddles, in which the larvae live Wasp years are often years with a warm early summer, giving the start-up communities favorable conditions.

In the long term the frequency of the different animals change. Animals like the European adder, human fleas, dog fleas, bed bugs and body lice are no longer as common as they were in the past. Head lice have had three common periods in Denmark in the 1900s – During the Two World Wars and in the early 1980s. Now it seems that once again the problem relatively under control. However, cat fleas have become increasingly common since the 1970s.They have become common and will probably continue to be so for a few more years.

J F M A M J J A S O N D 0 = Above average / 1 = Maximum
0 0 1             0 0 0 Dog fur mite
      1 0 0             Bird flea
      0 1 0 0   0       Pidgeon tick
        1 0   0         Stable flies
        0 1 0 0         Kissing bugs
        0 1 0 0         Swift louse fly
        0 1 0 0 0 0     Castor bean tick
        0 1 0           Mosquitoes
          1 0           Biting midges
          1 0 0         Stenepteryx hirundinis
        0 0 1 0         European adder (Lat. Vipera berus)
        0 0 1 0         Honey bee
          0 1 0         Bumblebee
          0 1 0         Horse-flies
            1 0         Hornets
            0 1 0 0 0   Cat fleas
            0 1   0 0   Thrips
0             1 0 0 0   The crab louse
      0 0 0 0 0 1       Bird mites
          0 0 0 1 0     Hedgehog fleas
0 0           0 1 0 0   Head louse (Lat. Pediculus humanus capitis)
              0 1 0 0   Bedbugs
0 0             0 1 0 0 Itch mites